1
|
Liu R, Wang M, Zheng T, Zhang R, Li N, Chen Z, Yan H, Shi Q. An artificial intelligence-based risk prediction model of myocardial infarction. BMC Bioinformatics 2022; 23:217. [PMID: 35672659 PMCID: PMC9175344 DOI: 10.1186/s12859-022-04761-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 05/30/2022] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Myocardial infarction can lead to malignant arrhythmia, heart failure, and sudden death. Clinical studies have shown that early identification of and timely intervention for acute MI can significantly reduce mortality. The traditional MI risk assessment models are subjective, and the data that go into them are difficult to obtain. Generally, the assessment is only conducted among high-risk patient groups. OBJECTIVE To construct an artificial intelligence-based risk prediction model of myocardial infarction (MI) for continuous and active monitoring of inpatients, especially those in noncardiovascular departments, and early warning of MI. METHODS The imbalanced data contain 59 features, which were constructed into a specific dataset through proportional division, upsampling, downsampling, easy ensemble, and w-easy ensemble. Then, the dataset was traversed using supervised machine learning, with recursive feature elimination as the top-layer algorithm and random forest, gradient boosting decision tree (GBDT), logistic regression, and support vector machine as the bottom-layer algorithms, to select the best model out of many through a variety of evaluation indices. RESULTS GBDT was the best bottom-layer algorithm, and downsampling was the best dataset construction method. In the validation set, the F1 score and accuracy of the 24-feature downsampling GBDT model were both 0.84. In the test set, the F1 score and accuracy of the 24-feature downsampling GBDT model were both 0.83, and the area under the curve was 0.91. CONCLUSION Compared with traditional models, artificial intelligence-based machine learning models have better accuracy and real-time performance and can reduce the occurrence of in-hospital MI from a data-driven perspective, thereby increasing the cure rate of patients and improving their prognosis.
Collapse
Affiliation(s)
- Ran Liu
- MOE Key Lab for Neuroinformation, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054 Sichuan China
- Engineering Research Center of Medical Information Technology, Ministry of Education, West China Hospital of Sichuan University, Chengdu, 610041 Sichuan China
| | - Miye Wang
- Engineering Research Center of Medical Information Technology, Ministry of Education, West China Hospital of Sichuan University, Chengdu, 610041 Sichuan China
| | - Tao Zheng
- Engineering Research Center of Medical Information Technology, Ministry of Education, West China Hospital of Sichuan University, Chengdu, 610041 Sichuan China
| | - Rui Zhang
- Engineering Research Center of Medical Information Technology, Ministry of Education, West China Hospital of Sichuan University, Chengdu, 610041 Sichuan China
| | - Nan Li
- Engineering Research Center of Medical Information Technology, Ministry of Education, West China Hospital of Sichuan University, Chengdu, 610041 Sichuan China
| | - Zhongxiu Chen
- Department of Cardiology, West China Hospital of Sichuan University, Chengdu, 610041 Sichuan China
| | - Hongmei Yan
- MOE Key Lab for Neuroinformation, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054 Sichuan China
| | - Qingke Shi
- Engineering Research Center of Medical Information Technology, Ministry of Education, West China Hospital of Sichuan University, Chengdu, 610041 Sichuan China
| |
Collapse
|
2
|
Khan Y, Butt MA, Kazanskiy NL, Khonina SN. Numerical Study of Fabrication-Related Effects of the Structural-Profile on the Performance of a Dielectric Photonic Crystal-Based Fluid Sensor. MATERIALS 2022; 15:ma15093277. [PMID: 35591609 PMCID: PMC9104057 DOI: 10.3390/ma15093277] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Revised: 04/28/2022] [Accepted: 04/29/2022] [Indexed: 02/06/2023]
Abstract
In this work, fabrication of a dielectric photonic crystal device and numerical study of its spectral characteristics as a refractive index sensor are presented for near infrared range. The proposed nanosensor device is composed of low-cost dielectric materials, i.e., silicon dioxide and niobium pentoxide, and is fabricated using focused ion-beam milling lithography. In the first part, the fabrication process of the device is discussed, along with the process parameters and their effects on the structural properties of the resulting photonic crystal elements. In the second part, the device is numerically tested as a sensor for the biological refractive index range of 1.33 to 1.4. The performance considerations of the biosensor device are studied for 12 different structural profiles based on the fabrication results. It is shown that the angular-wall-profile of the fabricated structures downgrades the performance of the sensor, and the optimum value of hole depth should be in the range of 930–1500 nm to get the best performance. A sensitivity of 185.117 nm/RIU and a figure of merit of 9.7 were recorded for the optimum design of the device; however, a maximum sensitivity of 296.183 nm/RIU and a figure-of-merit of 13.184 RIU−1 were achieved. The device is recommended for a variety of biosensing applications due to its inert material properties, stable design and easy integration with fiber-optic setups.
Collapse
Affiliation(s)
- Yousuf Khan
- Technological Electronics, Institute of Nanostructure Technologies and Analytics, University of Kassel, Heinrich-Plett-Str.40, 34132 Kassel, Germany
- Nanophotonics Research Group, Department of Electronic Engineering, Balochistan University of Information Technology, Engineering and Management Sciences, Quetta 87300, Pakistan
- Correspondence:
| | - Muhammad A. Butt
- Samara National Research University, 443086 Samara, Russia
- Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, Koszykowa 75, 00-662 Warszawa, Poland;
| | - Nikolay L. Kazanskiy
- Samara National Research University, 443086 Samara, Russia
- IPSI RAS-Branch of the FSRC “Crystallography and Photonics” RAS, 443001 Samara, Russia; (N.L.K.); (S.N.K.)
| | - Svetlana N. Khonina
- Samara National Research University, 443086 Samara, Russia
- IPSI RAS-Branch of the FSRC “Crystallography and Photonics” RAS, 443001 Samara, Russia; (N.L.K.); (S.N.K.)
| |
Collapse
|
3
|
Yeh CT, Barshilia D, Hsieh CJ, Li HY, Hsieh WH, Chang GE. Rapid and Highly Sensitive Detection of C-Reaction Protein Using Robust Self-Compensated Guided-Mode Resonance BioSensing System for Point-of-Care Applications. BIOSENSORS 2021; 11:523. [PMID: 34940280 PMCID: PMC8699450 DOI: 10.3390/bios11120523] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/12/2021] [Accepted: 12/15/2021] [Indexed: 05/24/2023]
Abstract
The rapid and sensitive detection of human C-reactive protein (CRP) in a point-of-care (POC) may be conducive to the early diagnosis of various diseases. Biosensors have emerged as a new technology for rapid and accurate detection of CRP for POC applications. Here, we propose a rapid and highly stable guided-mode resonance (GMR) optofluidic biosensing system based on intensity detection with self-compensation, which substantially reduces the instability caused by environmental factors for a long detection time. In addition, a low-cost LED serving as the light source and a photodetector are used for intensity detection and real-time biosensing, and the system compactness facilitates POC applications. Self-compensation relies on a polarizing beam splitter to separate the transverse-magnetic-polarized light and transverse-electric-polarized light from the light source. The transverse-electric-polarized light is used as a background signal for compensating noise, while the transverse-magnetic-polarized light is used as the light source for the GMR biosensor. After compensation, noise is drastically reduced, and both the stability and performance of the system are enhanced over a long period. Refractive index experiments revealed a resolution improvement by 181% when using the proposed system with compensation. In addition, the system was successfully applied to CRP detection, and an outstanding limit of detection of 1.95 × 10-8 g/mL was achieved, validating the proposed measurement system for biochemical reaction detection. The proposed GMR biosensing sensing system can provide a low-cost, compact, rapid, sensitive, and highly stable solution for a variety of point-of-care applications.
Collapse
Affiliation(s)
| | | | | | | | | | - Guo-En Chang
- Department of Mechanical Engineering, Advanced Institute of Manufacturing with High-Tech Innovations (AIM-HI), National Chung Cheng University, Minxiong Township 62102, Taiwan; (C.-T.Y.); (D.B.); (C.-J.H.); (H.-Y.L.); (W.-H.H.)
| |
Collapse
|
4
|
Le THH, Shimizu H, Morikawa K. Advances in Label-Free Detections for Nanofluidic Analytical Devices. MICROMACHINES 2020; 11:mi11100885. [PMID: 32977690 PMCID: PMC7598655 DOI: 10.3390/mi11100885] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 09/20/2020] [Accepted: 09/21/2020] [Indexed: 12/12/2022]
Abstract
Nanofluidics, a discipline of science and engineering of fluids confined to structures at the 1-1000 nm scale, has experienced significant growth over the past decade. Nanofluidics have offered fascinating platforms for chemical and biological analyses by exploiting the unique characteristics of liquids and molecules confined in nanospaces; however, the difficulty to detect molecules in extremely small spaces hampers the practical applications of nanofluidic devices. Laser-induced fluorescence microscopy with single-molecule sensitivity has been so far a major detection method in nanofluidics, but issues arising from labeling and photobleaching limit its application. Recently, numerous label-free detection methods have been developed to identify and determine the number of molecules, as well as provide chemical, conformational, and kinetic information of molecules. This review focuses on label-free detection techniques designed for nanofluidics; these techniques are divided into two groups: optical and electrical/electrochemical detection methods. In this review, we discuss on the developed nanofluidic device architectures, elucidate the mechanisms by which the utilization of nanofluidics in manipulating molecules and controlling light-matter interactions enhances the capabilities of biological and chemical analyses, and highlight new research directions in the field of detections in nanofluidics.
Collapse
Affiliation(s)
- Thu Hac Huong Le
- Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
- Correspondence: (T.H.H.L.); (H.S.); (K.M.)
| | - Hisashi Shimizu
- Collaborative Research Organization for Micro and Nano Multifunctional Devices (NMfD), The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
- Correspondence: (T.H.H.L.); (H.S.); (K.M.)
| | - Kyojiro Morikawa
- Collaborative Research Organization for Micro and Nano Multifunctional Devices (NMfD), The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
- Correspondence: (T.H.H.L.); (H.S.); (K.M.)
| |
Collapse
|
5
|
De-Eknamkul C, Zhang X, Zhao MQ, Huang W, Liu R, Johnson ATC, Cubukcu E. MoS 2-enabled dual-mode optoelectronic biosensor using a water soluble variant of μ-opioid receptor for opioid peptide detection. 2D MATERIALS 2020; 7:014004. [PMID: 32523701 PMCID: PMC7286605 DOI: 10.1088/2053-1583/ab5ae2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Owing to their unique electrical and optical properties, two-dimensional transition metal dichalcogenides have been extensively studied for their potential applications in biosensing. However, simultaneous utilization of both optical and electrical properties has been overlooked, yet it can offer enhanced accuracy and detection versitility. Here, we demonstrate a dual-mode optoelectronic biosensor based on monolayer molybdenum disulfide (MoS2) capable of producing simultaneous electrical and optical readouts of biomolecular signals. On a single platform, the biosensor exhibits a tunable photonic Fano-type optical resonance while also functioning as a field-effect transistor (FET) based on a optically transparent gate electrode. Furthermore, chemical vapor deposition grown MoS2 provides a clean surface for direct immobilization of a water-soluble variant of the μ-opioid receptor (wsMOR), via a nickel ion-mediated linker chemistry. We utilize a synthetic opioid peptide to show the operation of the electronic and optical sensing modes. The responses of both modes exhibit a similar trend with dynamic ranges of four orders of magnitude and detection limits of <1 nM. Our work explores the potential of a versatile multimodal sensing platform enabled by monolayer MoS2, since the integration of electrical and optical sensors on the same chip can offer flexibility in read-out and improve the accuracy in detection of low concentration targets.
Collapse
Affiliation(s)
- Chawina De-Eknamkul
- Department of NanoEngineering, University of California, San Diego, La Jolla, CA 92093-0448, United States of America
| | - Xingwang Zhang
- Department of NanoEngineering, University of California, San Diego, La Jolla, CA 92093-0448, United States of America
| | - Meng-Qiang Zhao
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, United States of America
| | - Wenzhuo Huang
- Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, CA 92093-0407, United States of America
| | - Renyu Liu
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States of America
| | - A T Charlie Johnson
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, United States of America
| | - Ertugrul Cubukcu
- Department of NanoEngineering, University of California, San Diego, La Jolla, CA 92093-0448, United States of America
- Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, CA 92093-0407, United States of America
| |
Collapse
|
6
|
Sivashanmugan K, Squire K, Kraai JA, Tan A, Zhao Y, Rorrer GL, Wang AX. Biological Photonic Crystal-Enhanced Plasmonic Mesocapsules: Approaching Single-Molecule Optofluidic-SERS Sensing. ADVANCED OPTICAL MATERIALS 2019; 7:1900415. [PMID: 32775144 PMCID: PMC7410161 DOI: 10.1002/adom.201900415] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Indexed: 05/05/2023]
Abstract
Surface-enhanced Raman scattering (SERS) sensing in microfluidic devices, namely optofluidic-SERS, suffers an intrinsic trade-off between mass transport and hot spot density, both of which are required for ultra-sensitive detection. To overcome this compromise, photonic crystal-enhanced plasmonic mesocapsules are synthesized, utilizing diatom biosilica decorated with in-situ growth silver nanoparticles (Ag NPs). In our optofluidic-SERS testing, 100× higher enhancement factors and greater than 1,000× better detection limit were achieved compared with traditional colloidal Ag NPs, the improvement of which is attributed to unique properties of the mesocapsules. First, the porous diatom biosilica frustules serve as carrier capsules for high density Ag NPs that form high density plasmonic hot-spots. Second, the submicron-pores embedded in the frustule walls not only create a large surface-to-volume ratio allowing for effective analyte capture, but also enhance the local optical field through the photonic crystal effect. Last, the mesocapsules provide effective mixing with analytes as they are flowing inside the microfluidic channel. The reported mesocapsules achieved single molecule detection of Rhodamine 6G in microfluidic devices and were further utilized to detect 1 nM of benzene and chlorobenzene compounds in tap water with near real-time response, which successfully overcomes the constraint of traditional optofluidic sensing.
Collapse
Affiliation(s)
- Kundan Sivashanmugan
- School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR 97331, USA
| | - Kenneth Squire
- School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR 97331, USA
| | - Joseph A. Kraai
- School of Chemical, Biological, and Ecological Engineering, Oregon State University, Corvallis, OR 97331, USA
| | - Ailing Tan
- School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR 97331, USA
- School of Information Science and Engineering, The Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province, Yanshan University, Qinhuangdao 066004, China
| | - Yong Zhao
- School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR 97331, USA
- School of Electrical Engineering, The Key Laboratory of Measurement Technology and Instrumentation of Hebei Province, Yanshan University, Qinhuangdao, 066004, China
| | - Gregory L. Rorrer
- School of Chemical, Biological, and Ecological Engineering, Oregon State University, Corvallis, OR 97331, USA
| | - Alan X. Wang
- School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, OR 97331, USA
| |
Collapse
|
7
|
Zhu X, Cicek A, Li Y, Yanik AA. Plasmofluidic Microlenses for Label-Free Optical Sorting of Exosomes. Sci Rep 2019; 9:8593. [PMID: 31197196 PMCID: PMC6565621 DOI: 10.1038/s41598-019-44801-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 05/16/2019] [Indexed: 11/20/2022] Open
Abstract
Optical chromatography is a powerful optofluidic technique enabling label-free fractionation of microscopic bioparticles from heterogenous mixtures. However, sophisticated instrumentation requirements for precise alignment of optical scattering and fluidic drag forces is a fundamental shortcoming of this technique. Here, we introduce a subwavelength thick (<200 nm) Optofluidic PlasmonIC (OPtIC) microlens that effortlessly achieves objective-free focusing and self-alignment of opposing optical scattering and fluidic drag forces for selective separation of exosome size bioparticles. Our optofluidic microlens provides a self-collimating mechanism for particle trajectories with a spatial dispersion that is inherently minimized by the optical gradient and radial fluidic drag forces working together to align the particles along the optical axis. We demonstrate that this facile platform facilitates complete separation of small size bioparticles (i.e., exosomes) from a heterogenous mixture through negative depletion and provides a robust selective separation capability for same size nanoparticles based on their differences in chemical composition. Unlike existing optical chromatography techniques that require complicated instrumentation (lasers, objectives and precise alignment stages), our OPtIC microlenses with a foot-print of 4 μm × 4 μm open up the possibility of multiplexed and high-throughput sorting of nanoparticles on a chip using low-cost broadband light sources.
Collapse
Affiliation(s)
- Xiangchao Zhu
- Department of Electrical and Computer Engineering, University of California, Santa Cruz, CA, 95064, USA
| | - Ahmet Cicek
- Department of Nanoscience and Nanotechnology, Burdur Mehmet Akif Ersoy University, Burdur, 15030, Turkey
| | - Yixiang Li
- Department of Electrical and Computer Engineering, University of California, Santa Cruz, CA, 95064, USA
| | - Ahmet Ali Yanik
- Department of Electrical and Computer Engineering, University of California, Santa Cruz, CA, 95064, USA. .,California Institute for Quantitative Biosciences (QB3), University of California, Santa Cruz, CA, 95064, USA.
| |
Collapse
|
8
|
Cetin AE, Topkaya SN. Photonic crystal and plasmonic nanohole based label-free biodetection. Biosens Bioelectron 2019; 132:196-202. [DOI: 10.1016/j.bios.2019.02.047] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 02/14/2019] [Accepted: 02/25/2019] [Indexed: 11/27/2022]
|
9
|
Borta P, Monniello L, Kurdi ME, Saada S, Sauvage S, Girard H, Checoury X. Increasing the angular sensitivity of two-dimensional photonic crystal based sensors to arbitrary values. OPTICS EXPRESS 2019; 27:1578-1589. [PMID: 30696222 DOI: 10.1364/oe.27.001578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 01/02/2019] [Indexed: 06/09/2023]
Abstract
A new design of photonic crystal (PhC) for optical sensing using guided mode resonance (GMR) is presented. We theoretically show that angular sensitivity is inversely proportional to the group velocity of the probed mode and can be made arbitrarily high in a properly designed PhC. PhCs made in polycrystalline diamond on insulator are fabricated. The angular sensitivity dependence is validated. We measured modes with group velocity of c/80 at a wavelength of 800 nm. A sensitivity in the order of 500 ° per refractive index unit is inferred, a value much larger than the one usually encountered in PhCs.
Collapse
|
10
|
Surdo S, Carpignano F, Merlo S, Barillaro G. Near-Infrared Silicon Photonic Crystals with High-Order Photonic Bandgaps for High-Sensitivity Chemical Analysis of Water-Ethanol Mixtures. ACS Sens 2018; 3:2223-2231. [PMID: 30380852 DOI: 10.1021/acssensors.8b00933] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Aqueous solutions of alcohols are used in several applications, from pharmaceutics and biology, to chemical, biofuel, and food industries. Nonetheless, development of a simple, inexpensive, and portable sensing device for the quantification of water in water-ethanol mixtures remains a significant challenge. Photonic crystals (PhCs) operating at very high-order photonic bandgaps (PBGs) offer remarkable opportunities for the realization of chemical sensors with high sensitivity and low detection limit. However, high-order PhC structures have been mostly confined to mere theoretical speculations so far, their effective realization requiring microfabrication tools enabling the control of periodic refractive index modulations at the submicrometric scale with extremely high accuracy and precision. Here, we report both experimental and theoretical results on high-sensitivity chemical analysis using vertical, silicon/air 1D-PhCs with spatial period of 10 and 20 μm (namely, over 10 times the operation wavelength) featuring ultra-high-order PBGs in the near-infrared region (namely, up to 50th at 1.1 μm). Fabrication of high-order 1D-PhCs was carried out by electrochemical micromachining (ECM) of silicon, which allowed both surface roughness and deviation from vertical of etched structures to be controlled below 5 nm and 0.1%, respectively. Optical characterization of ECM-fabricated 1D-PhCs, which was performed by acquiring reflectivity spectra over the wavelength range 1-1.7 μm, highlighted the presence of ultra-high-order PBGs with minor optical losses (i.e., <1 dB in reflectivity) separated by deep reflectivity notches with high Q-factors (i.e., >6000), in good agreement with theoretical calculations. Remarkably, the use of high-order 1D-PhCs as refractometric transducers for the quantitative detection of traces of water in water-ethanol mixtures, allowed high sensitivity (namely, either 1000 nm/RIU or ∼0.4 nm/% of water), good detection limit (namely, 5 × 10-3 RIU or ∼10% water), and excellent resolution (namely, either 6 × 10-4 RIU or 1.6% of water) to be reliably achieved on a detection volume of about 168 fL.
Collapse
Affiliation(s)
- Salvatore Surdo
- Dipartimento di Ingegneria dell’Informazione, Università di Pisa, via G. Caruso 16, 56122 Pisa, Italy
- Nanophysics, Istituto Italiano di Tecnologia, Via Morego 30, 16123 Genova, Italy
| | - Francesca Carpignano
- Dipartimento di Ingegneria Industriale e dell’Informazione, Università di Pavia, Via Ferrata 5, 27100 Pavia, Italy
- MEMS Technology Development, AMG Group, STMicroelectronics, Via C. Olivetti 2, 20041 Agrate Brianza, Italy
| | - Sabina Merlo
- Dipartimento di Ingegneria Industriale e dell’Informazione, Università di Pavia, Via Ferrata 5, 27100 Pavia, Italy
| | - Giuseppe Barillaro
- Dipartimento di Ingegneria dell’Informazione, Università di Pisa, via G. Caruso 16, 56122 Pisa, Italy
| |
Collapse
|
11
|
Sun J, Maeno K, Aki S, Sueyoshi K, Hisamoto H, Endo T. Design and Fabrication of a Visible-Light-Compatible, Polymer-Based Photonic Crystal Resonator and Waveguide for Sensing Applications. MICROMACHINES 2018; 9:E410. [PMID: 30424343 PMCID: PMC6187389 DOI: 10.3390/mi9080410] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 08/02/2018] [Accepted: 08/14/2018] [Indexed: 12/11/2022]
Abstract
In this paper, we have proposed a polymer-based photonic crystal (PhC) resonator, with multiple sizes of cavities, and a waveguide to be used as highly sensitive optical sensor components. Properties of the proposed PhC were simulated by the finite-difference time-domain method, and the polymer-based PhC resonator and waveguide were fabricated on a photoresist (polymer) by electron beam lithography, which was prepared on an Au-layer-deposited Si substrate. We detected the resonant light that penetrated through the waveguide and was trapped in the PhC resonator. Optical characteristics of the fabricated PhC were evaluated by detecting the polymer layer deposition process by using the layer-by-layer (LbL) method to deposit polymer layers. As a result, by using an optimized design of a polymer-based PhC resonator with a long cavity (equivalent to a defect of three holes), the PhC structure changes caused by LbL deposition lead to changes in resonant light wavelength (peak shift: 5.26 nm/layer). Therefore, we suggest that a PhC resonator and a waveguide is applicable as an optical sensor.
Collapse
Affiliation(s)
- Jiayi Sun
- Department of Applied Chemistry, Osaka Prefecture University, Osaka 599-8531, Japan.
| | - Kenichi Maeno
- Department of Applied Chemistry, Osaka Prefecture University, Osaka 599-8531, Japan.
| | - Shoma Aki
- Department of Applied Chemistry, Osaka Prefecture University, Osaka 599-8531, Japan.
| | - Kenji Sueyoshi
- Department of Applied Chemistry, Osaka Prefecture University, Osaka 599-8531, Japan.
| | - Hideaki Hisamoto
- Department of Applied Chemistry, Osaka Prefecture University, Osaka 599-8531, Japan.
| | - Tatsuro Endo
- Department of Applied Chemistry, Osaka Prefecture University, Osaka 599-8531, Japan.
- Japan Science and Technology Agency (JST) Precursory Research for Embryonic Science and Technology (PRESTO), Tokyo 102-8666, Japan.
| |
Collapse
|
12
|
Lu X, Zhang T, Wan R, Xu Y, Zhao C, Guo S. Numerical investigation of narrowband infrared absorber and sensor based on dielectric-metal metasurface. OPTICS EXPRESS 2018; 26:10179-10187. [PMID: 29715958 DOI: 10.1364/oe.26.010179] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Metasurfaces are investigated intensively for biophotonics applications due to their resonant wavelength flexibly tuned in the near infrared region specially matching biological tissues. Here, we present numerically a metasurface structure combining dielectric resonance with surface plasmon mode of a metal plane, which is a perfect absorber with a narrow linewidth 10 nm wide and quality factor 120 in the near infrared regime. As a sensor, its bulk sensitivity and bulk figure of merit reach respectively 840 nm/RIU and 84/RIU, while its surface sensitivity and surface figure of merit are respectively 1 and 0.1/nm. For different types of adsorbate layers with the same thickness of 8 nm, its surface sensitivity and figure of merit are respectively 32.3 and 3.2/RIU. The enhanced electric field is concentrated on top of dielectric patch ends and in the patch ends simultaneously. Results show that the presented structure has high surface (and bulk) sensing capability in sensing applications due to its narrow linewidth and deep modulation depth. This could pave a new route toward dielectric-metal metasurface in biosensing applications, such as early disease detections and designs of neural stem cell sensing platforms.
Collapse
|
13
|
Peng W, Chen Y, Ai W, Zhang D, Song H, Xiong H, Huang P. CMOS-Compatible Fabrication for Photonic Crystal-Based Nanofluidic Structure. NANOSCALE RESEARCH LETTERS 2017; 12:103. [PMID: 28209025 PMCID: PMC5307410 DOI: 10.1186/s11671-017-1849-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 01/13/2017] [Indexed: 05/30/2023]
Abstract
Photonic crystal (PC)-based devices have been widely used since 1990s, while PC has just stepped into the research area of nanofluidic. In this paper, photonic crystal had been used as a complementary metal oxide semiconductors (CMOS) compatible part to create a nanofluidic structure. A nanofluidic structure prototype had been fabricated with CMOS-compatible techniques. The nanofluidic channels were sealed by direct bonding polydimethylsiloxane (PDMS) and the periodic gratings on photonic crystal structure. The PC was fabricated on a 4-in. Si wafer with Si3N4 as the guided mode layer and SiO2 film as substrate layer. The higher order mode resonance wavelength of PC-based nanofluidic structure had been selected, which can confine the enhanced electrical field located inside the nanochannel area. A design flow chart was used to guide the fabrication process. By optimizing the fabrication device parameters, the periodic grating of PC-based nanofluidic structure had a high-fidelity profile with fill factor at 0.5. The enhanced electric field was optimized and located within the channel area, and it can be used for PC-based nanofluidic applications with high performance.
Collapse
Affiliation(s)
- Wang Peng
- School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074 China
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 USA
- Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 USA
- Flexible Electronics Research Center, Huazhong University of Science and Technology, Wuhan, 430074 China
| | - Youping Chen
- School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074 China
| | - Wu Ai
- School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074 China
| | - Dailin Zhang
- School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074 China
| | - Han Song
- School of Mechanical and Electronic Engineering, Wuhan University of Technology, Wuhan, 430070 China
| | - Hui Xiong
- School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074 China
| | - Pengcheng Huang
- School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074 China
| |
Collapse
|
14
|
Rigamonti G, Guardamagna M, Bello V, Marconi S, Auricchio F, Merlo S. Flow-through micro-capillary refractive index sensor based on T/R spectral shift monitoring. BIOMEDICAL OPTICS EXPRESS 2017; 8:4438-4453. [PMID: 29082076 PMCID: PMC5654791 DOI: 10.1364/boe.8.004438] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 07/25/2017] [Accepted: 07/31/2017] [Indexed: 06/07/2023]
Abstract
We present a flow-through refractive index sensor for measuring the concentration of glucose solutions based on the application of rectangular glass micro-capillaries, with channel depth of 50 µm and 30 µm. A custom designed and 3D printed polymeric shell protects the tiny capillaries, ensuring an easier handling and interconnection with the macro-fluidic path. By illuminating the capillary with broadband radiation centered at λ~1.55 µm, both the transmitted (T) and reflected (R) optical spectrum from the capillary are detected with an optical spectrum analyzer, exploiting an all-fiber setup. Monitoring the spectral shift of the ratio T/R in response to increasing concentration of glucose solutions in water we have obtained sensitivities up to 530.9 nm/RIU and limit of detection in the range of 10-5-10-4 RIU. Experimental results are in agreement with the theoretically predicted principle of operation. After the demonstration of amplitude detection at a single wavelength, we finally discuss the impact of the capillary parameters on the sensitivity.
Collapse
Affiliation(s)
- Giulia Rigamonti
- Dipartimento di Ingegneria Industriale e dell’Informazione, University of Pavia, 27100, Pavia, Italy
| | - Marco Guardamagna
- Dipartimento di Ingegneria Industriale e dell’Informazione, University of Pavia, 27100, Pavia, Italy
| | - Valentina Bello
- Dipartimento di Ingegneria Industriale e dell’Informazione, University of Pavia, 27100, Pavia, Italy
| | - Stefania Marconi
- Dipartimento di Ingegneria Civile e Architettura, University of Pavia, 27100, Pavia, Italy
| | - Ferdinando Auricchio
- Dipartimento di Ingegneria Civile e Architettura, University of Pavia, 27100, Pavia, Italy
| | - Sabina Merlo
- Dipartimento di Ingegneria Industriale e dell’Informazione, University of Pavia, 27100, Pavia, Italy
| |
Collapse
|
15
|
Inan H, Poyraz M, Inci F, Lifson MA, Baday M, Cunningham BT, Demirci U. Photonic crystals: emerging biosensors and their promise for point-of-care applications. Chem Soc Rev 2017; 46:366-388. [PMID: 27841420 PMCID: PMC5529146 DOI: 10.1039/c6cs00206d] [Citation(s) in RCA: 169] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Biosensors are extensively employed for diagnosing a broad array of diseases and disorders in clinical settings worldwide. The implementation of biosensors at the point-of-care (POC), such as at primary clinics or the bedside, faces impediments because they may require highly trained personnel, have long assay times, large sizes, and high instrumental cost. Thus, there exists a need to develop inexpensive, reliable, user-friendly, and compact biosensing systems at the POC. Biosensors incorporated with photonic crystal (PC) structures hold promise to address many of the aforementioned challenges facing the development of new POC diagnostics. Currently, PC-based biosensors have been employed for detecting a variety of biotargets, such as cells, pathogens, proteins, antibodies, and nucleic acids, with high efficiency and selectivity. In this review, we provide a broad overview of PCs by explaining their structures, fabrication techniques, and sensing principles. Furthermore, we discuss recent applications of PC-based biosensors incorporated with emerging technologies, including telemedicine, flexible and wearable sensing, smart materials and metamaterials. Finally, we discuss current challenges associated with existing biosensors, and provide an outlook for PC-based biosensors and their promise at the POC.
Collapse
Affiliation(s)
- Hakan Inan
- Demirci Bio-Acoustic-MEMS in Medicine (BAMM) Laboratory, Stanford University School of Medicine, Department of Radiology, Canary Center at Stanford for Cancer Early Detection, 3155 Porter Drive, Palo Alto, CA 94304, USA.
| | - Muhammet Poyraz
- Demirci Bio-Acoustic-MEMS in Medicine (BAMM) Laboratory, Stanford University School of Medicine, Department of Radiology, Canary Center at Stanford for Cancer Early Detection, 3155 Porter Drive, Palo Alto, CA 94304, USA. and Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Fatih Inci
- Demirci Bio-Acoustic-MEMS in Medicine (BAMM) Laboratory, Stanford University School of Medicine, Department of Radiology, Canary Center at Stanford for Cancer Early Detection, 3155 Porter Drive, Palo Alto, CA 94304, USA.
| | - Mark A Lifson
- Demirci Bio-Acoustic-MEMS in Medicine (BAMM) Laboratory, Stanford University School of Medicine, Department of Radiology, Canary Center at Stanford for Cancer Early Detection, 3155 Porter Drive, Palo Alto, CA 94304, USA.
| | - Murat Baday
- Demirci Bio-Acoustic-MEMS in Medicine (BAMM) Laboratory, Stanford University School of Medicine, Department of Radiology, Canary Center at Stanford for Cancer Early Detection, 3155 Porter Drive, Palo Alto, CA 94304, USA.
| | - Brian T Cunningham
- Department of Electrical and Computer Engineering, Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
| | - Utkan Demirci
- Demirci Bio-Acoustic-MEMS in Medicine (BAMM) Laboratory, Stanford University School of Medicine, Department of Radiology, Canary Center at Stanford for Cancer Early Detection, 3155 Porter Drive, Palo Alto, CA 94304, USA. and Department of Electrical Engineering (by courtesy), Stanford University, Stanford, CA, USA
| |
Collapse
|
16
|
Feng S, Jiang JH, Rashid AA, John S. Biosensor architecture for enhanced disease diagnostics: lab-in-a-photonic-crystal. OPTICS EXPRESS 2016; 24:12166-12191. [PMID: 27410136 DOI: 10.1364/oe.24.012166] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A conceptual lab-in-a-photonic-crystal biosensor is demonstrated that can multiplex four or more distinct disease-markers and distinguish their presence and combinations simultaneously with unique spectral fingerprints. This biosensor consists of a photonic-band-gap, multi-mode waveguide coupled to surface modes on either side, encased in a glass slide with microfluidic channels. The spectral fingerprints consist of multiple peaks in optical transmission vs. frequency that respond sensitively and uniquely in both frequency shift and nonmonotonic change of peak transmittance levels to various analyte bindings. This special property enables complete, logical determination of twelve different combinations of four distinct disease-markers through one scan of the transmission spectrum. The results reveal unique phenomena such as switching between the strong-coupling and weak-coupling combinations of surface states by analyte binding at different locations along the central waveguide. The unconventional transmission spectra are explained using a Landauer-Büttiker, multiple-scattering, transmission theory that reproduces the main features of the exact finite-difference-time-domain simulation.
Collapse
|
17
|
Optimization of high-Q coupled nanobeam cavity for label-free sensing. SENSORS 2015; 15:25868-81. [PMID: 26473870 PMCID: PMC4634518 DOI: 10.3390/s151025868] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 09/29/2015] [Accepted: 10/09/2015] [Indexed: 11/17/2022]
Abstract
We numerically and experimentally investigated the lateral coupling between photonic crystal (PhC) nanobeam (NB) cavities, pursuing high sensitivity and figure of merit (FOM) label-free biosensor. We numerically carried out 3D finite-difference time-domain (3D-FDTD) and the finite element method (FEM) simulations. We showed that when two PhC NB cavities separated by a small gap are evanescently coupled, the variation in the gap width significantly changes the coupling efficiency between the two coupled NB cavities and the resulting resonant frequencies split. Experimentally, we fabricated laterally-coupled PhC NB cavities using (InGaAsP) layer on the InP substrate. For sensing, we showed that the laterally coupled PhC NB cavities sensor exhibits higher sensitivity than the single PhC NB cavity. The higher sensitivity of laterally coupled PhC NB cavities is due to the strong evanescent coupling between nearby PhC NB cavities, which depends on the gap width and it is attributed to the large confinement of the electromagnetic field in the gap (air or liquid). As a result of the lateral coupling, both even (symmetric) and odd (asymmetric) modes exist. We show that even modes are more sensitive than odd modes. In addition, higher-order modes exhibit higher sensitivity. Hence, we characterized and examined the fabricated PhC NB cavity as a label-free biosensor, and it exhibits high figure of merit due to its high Q-factor. This illustrates a potentially useful method for optical sensing at nanoscale.
Collapse
|
18
|
Ku YF, Li HY, Hsieh WH, Chau LK, Chang GE. Enhanced sensitivity in injection-molded guided-mode-resonance sensors via low-index cavity layers. OPTICS EXPRESS 2015; 23:14850-9. [PMID: 26072843 DOI: 10.1364/oe.23.014850] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
We present an investigation on the use of low-index cavity layers to enhance the sensitivity of injection-molded guided-mode resonance (GMR) sensors. By adjusting the sputtering parameters, a low-index cavity layer is created at the interface between the waveguide layer and the substrate. Refractive index measurements show that a sensitivity enhancement of up to 220% is achieved with a cavity layer, in comparison to a reference GMR sensor without a cavity layer. Finite-element-method simulations were performed, and the results indicate that the cavities significantly redistribute the resonance mode profile and thus enhances the sensitivity. The present investigation demonstrates a new method for enhancing the sensitivity of injection-molded GMR sensors for high-sensitivity label-free biosensing.
Collapse
|
19
|
Baker JE, Sriram R, Miller BL. Two-dimensional photonic crystals for sensitive microscale chemical and biochemical sensing. LAB ON A CHIP 2015; 15:971-990. [PMID: 25563402 PMCID: PMC4315696 DOI: 10.1039/c4lc01208a] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Photonic crystals - optical devices able to respond to changes in the refractive index of a small volume of space - are an emerging class of label-free chemical- and bio-sensors. This review focuses on one class of photonic crystal, in which light is confined to a patterned planar material layer of sub-wavelength thickness. These devices are small (on the order of tens to hundreds of microns square), suitable for incorporation into lab-on-a-chip systems, and in theory can provide exceptional sensitivity. We introduce the defining characteristics and basic operation of two-dimensional photonic crystal sensors, describe variations of their basic design geometry, and summarize reported detection results from chemical and biological sensing experiments.
Collapse
Affiliation(s)
- James E. Baker
- Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627 , USA
| | - Rashmi Sriram
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14627, USA
| | - Benjamin L. Miller
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14627, USA
- Department of Dermatology and Department of Biochemistry and Biophysics, University of Rochester, 601 Elmwood Avenue, Box 697, Rochester, NY 14627, USA
| |
Collapse
|
20
|
Song M, Yu H, Wang C, Yao N, Pu M, Luo J, Zhang Z, Luo X. Sharp Fano resonance induced by a single layer of nanorods with perturbed periodicity. OPTICS EXPRESS 2015; 23:2895-2903. [PMID: 25836151 DOI: 10.1364/oe.23.002895] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In this paper, we report the formation of extremely sharp (Quality factor Q~ + ∞) FR in a single layer of dielectric nanorods with perturbed periodicity. The interference between the broadband Fabry-Perot (F-P) resonance and defect induced dark mode results in refractive index sensitivity (S) of 1312.75 nm/RIU and figure of merit (FOM) of 500, offering an excellent platform for biological sensing and detection.
Collapse
|
21
|
Lin PT, Kwok SW, Lin HYG, Singh V, Kimerling LC, Whitesides GM, Agarwal A. Mid-infrared spectrometer using opto-nanofluidic slot-waveguide for label-free on-chip chemical sensing. NANO LETTERS 2014; 14:231-238. [PMID: 24328355 DOI: 10.1021/nl403817z] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A mid-infrared (mid-IR) spectrometer for label-free on-chip chemical sensing was developed using an engineered nanofluidic channel consisting of a Si-liquid-Si slot-structure. Utilizing the large refractive index contrast (Δn ∼ 2) between the liquid core of the waveguide and the Si cladding, a broadband mid-IR lightwave can be efficiently guided and confined within a nanofluidic capillary (≤100 nm wide). The optical-field enhancement, together with the direct interaction between the probe light and the analyte, increased the sensitivity for chemical detection by 50 times when compared to evanescent-wave sensing. This spectrometer distinguished several common organic liquids (e.g., n-bromohexane, toluene, isopropanol) accurately and could determine the ratio of chemical species (e.g., acetonitrile and ethanol) at low concentration (<5 μL/mL) in a mixture through spectral scanning over their characteristic absorption peaks in the mid-IR regime. The combination of CMOS-compatible planar mid-IR microphotonics, and a high-throughput nanofluidic sensor system, provides a unique platform for chemical detection.
Collapse
Affiliation(s)
- Pao Tai Lin
- Microphotonics Center, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | | | | | | | | | | | | |
Collapse
|
22
|
Huang M, Galarreta BC, Cetin AE, Altug H. Actively transporting virus like analytes with optofluidics for rapid and ultrasensitive biodetection. LAB ON A CHIP 2013; 13:4841-7. [PMID: 24170146 DOI: 10.1039/c3lc50814e] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Effective analyte delivery is essential to achieve rapid and sensitive biodetection systems. In this article, we present an actively controlled fluidic system integrated with a suspended plasmonic nanohole sensor to achieve superior analyte delivery efficiency and ultrafast sensor response, as compared to conventional fluidic systems. 70 nm sized virus like analyte solution is used to experimentally demonstrate the system performance improvements. Sensor response time is reduced by one order of magnitude as compared to the conventional methods. A seven orders of magnitude dynamic concentration range from 10(3) to 10(9) particles mL(-1) is quantified, corresponding to a concentration window relevant to clinical diagnosis and drug screening. Our non-destructive detection system, by enabling efficient analyte delivery, fast sensing response and minimal sample volume, opens up opportunities for sensitive, rapid and real-time virus detection in infectious disease control and point-of-care applications.
Collapse
Affiliation(s)
- Min Huang
- Electrical and Computer Engineering Department, Boston University, Boston, MA, USA
| | | | | | | |
Collapse
|
23
|
Nicolaou C, Lau WT, Gad R, Akhavan H, Schilling R, Levi O. Enhanced detection limit by dark mode perturbation in 2D photonic crystal slab refractive index sensors. OPTICS EXPRESS 2013; 21:31698-712. [PMID: 24514742 DOI: 10.1364/oe.21.031698] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
We demonstrate for the first time a 300nm thick, 300μm × 300μm 2D dielectric photonic crystal slab membrane with a quality factor of 10,600 by coupling light to slightly perturbed dark modes through alternating nano-hole sizes. The newly created fundamental guided resonances greatly reduce nano-fabrication accuracy requirements. Moreover, we created a new layer architecture resulting in electric field enhancement at the interface between the slab and sensing regions, and spectral sensitivity of >800 nm/RIU, that is, >0.8 of the single-mode theoretical upper limit of spectral sensitivity.
Collapse
|
24
|
Grepstad JO, Kaspar P, Johansen IR, Solgaard O, Sudbø A. Detection of single nano-defects in photonic crystals between crossed polarizers. OPTICS EXPRESS 2013; 21:31375-31389. [PMID: 24514712 DOI: 10.1364/oe.21.031375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We investigate, by simulations and experiments, the light scattering of small particles trapped in photonic crystal membranes supporting guided resonance modes. Our results show that, due to amplified Rayleigh small particle scattering, such membranes can be utilized to make a sensor that can detect single nano-particles. We have designed a biomolecule sensor that uses cross-polarized excitation and detection for increased sensitivity. Estimated using Rayleigh scattering theory and simulation results, the current fabricated sensor has a detection limit of 26 nm, corresponding to the size of a single virus. The sensor can potentially be made both cheap and compact, to facilitate use at point-of-care.
Collapse
|
25
|
Martínez LJ, Huang N, Ma J, Lin C, Jaquay E, Povinelli ML. Design and optical characterization of high-Q guided-resonance modes in the slot-graphite photonic crystal lattice. OPTICS EXPRESS 2013; 21:30975-30983. [PMID: 24514670 DOI: 10.1364/oe.21.030975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A new photonic crystal structure is generated by using a regular graphite lattice as the base and adding a slot in the center of each unit cell to enhance field confinement. The theoretical Q factor in an ideal structure is over 4 × 10(5). The structure was fabricated on a silicon-on-insulator wafer and optically characterized by transmission spectroscopy. The resonance wavelength and quality factor were measured as a function of slot height. The measured trends show good agreement with simulation.
Collapse
|
26
|
Estevez MC, Otte MA, Sepulveda B, Lechuga LM. Trends and challenges of refractometric nanoplasmonic biosensors: a review. Anal Chim Acta 2013; 806:55-73. [PMID: 24331040 DOI: 10.1016/j.aca.2013.10.048] [Citation(s) in RCA: 139] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 10/22/2013] [Accepted: 10/27/2013] [Indexed: 01/28/2023]
Abstract
Motivated by potential benefits such as sensor miniaturization, multiplexing opportunities and higher sensitivities, refractometric nanoplasmonic biosensing has profiled itself in a short time span as an interesting alternative to conventional Surface Plasmon Resonance (SPR) biosensors. This latter conventional sensing concept has been subjected during the last decades to strong commercialization, thereby strongly leaning on well-developed thin-film surface chemistry protocols. Not surprisingly, the examples found in literature based on this sensing concept are generally characterized by extensive analytical studies of relevant clinical and diagnostic problems. In contrast, the more novel Localized Surface Plasmon Resonance (LSPR) alternative finds itself in a much earlier, and especially, more fundamental stage of development. Driven by new fabrication methodologies to create nanostructured substrates, published work typically focuses on the novelty of the presented material, its optical properties and its use - generally limited to a proof-of-concept - as a label-free biosensing scheme. Given the different stages of development both SPR and LSPR sensors find themselves in, it becomes apparent that providing a comparative analysis of both concepts is not a trivial task. Nevertheless, in this review we make an effort to provide an overview that illustrates the progress booked in both fields during the last five years. First, we discuss the most relevant advances in SPR biosensing, including interesting analytical applications, together with different strategies that assure improvements in performance, throughput and/or integration. Subsequently, the remaining part of this work focuses on the use of nanoplasmonic sensors for real label-free biosensing applications. First, we discuss the motivation that serves as a driving force behind this research topic, together with a brief summary that comprises the main fabrication methodologies used in this field. Next, the sensing performance of LSPR sensors is examined by analyzing different parameters that can be invoked in order to quantitatively assess their overall sensing performance. Two aspects are highlighted that turn out to be especially important when trying to maximize their sensing performance, being (1) the targeted functionalization of the electromagnetic hotspots of the nanostructures, and (2) overcoming inherent negative influence that stem from the presence of a high refractive index substrate that supports the nanostructures. Next, although few in numbers, an overview is given of the most exhaustive and diagnostically relevant LSPR sensing assays that have been recently reported in literature, followed by examples that exploit inherent LSPR characteristics in order to create highly integrated and high-throughput optical biosensors. Finally, we discuss a series of considerations that, in our opinion, should be addressed in order to bring the realization of a stand-alone LSPR biosensor with competitive levels of sensitivity, robustness and integration (when compared to a conventional SPR sensor) much closer to reality.
Collapse
Affiliation(s)
- M-Carmen Estevez
- Institut Català de Nanociència i Nanotecnologia (ICN2), CSIC & CIBER-BBN, ICN2 Building Campus UAB, 08193 Bellaterra, Barcelona, Spain.
| | - Marinus A Otte
- Institut Català de Nanociència i Nanotecnologia (ICN2), CSIC & CIBER-BBN, ICN2 Building Campus UAB, 08193 Bellaterra, Barcelona, Spain
| | - Borja Sepulveda
- Institut Català de Nanociència i Nanotecnologia (ICN2), CSIC & CIBER-BBN, ICN2 Building Campus UAB, 08193 Bellaterra, Barcelona, Spain
| | - Laura M Lechuga
- Institut Català de Nanociència i Nanotecnologia (ICN2), CSIC & CIBER-BBN, ICN2 Building Campus UAB, 08193 Bellaterra, Barcelona, Spain
| |
Collapse
|
27
|
Nazirizadeh Y, von Oertzen F, Karrock T, Greve J, Gerken M. Enhanced sensitivity of photonic crystal slab transducers by oblique-angle layer deposition. OPTICS EXPRESS 2013; 21:18661-18670. [PMID: 23938782 DOI: 10.1364/oe.21.018661] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Photonic crystal slabs (PCS) are one of the major transducers for label-free, optical biosensing applications. In this paper we present oblique-angle layer deposition of the high index slab material as a method to improve the PCS sensitivity. In simulations and experiments we consider PCSs composed of a high index silicon monoxide layer on a nanostructured resist layer on a glass substrate. By mounting the substrate at an oblique angle with respect to the evaporation source, the high index material distribution on the nanostructured surface is modified due to shadowing effects. Finite-difference time-domain (FDTD) simulations were performed to predict bulk and surface sensitivities. In order to verify the simulation results we fabricated PCSs at various deposition angles using nanoimprint lithography to replicate a linear grating nanostructure into the resist layer and thermal evaporation for a 60-nm silicon monoxide deposition. The bulk sensitivities of these structures were measured using water-glycerol dilutions. A sensitivity improvement of 281% was obtained for PCSs fabricated at 45° deposition angle compared to normal incidence deposition.
Collapse
Affiliation(s)
- Yousef Nazirizadeh
- Institute of Electrical and Information Engineering, Christian-Albrechts-Universität zu Kiel, D-24143 Kiel, Germany.
| | | | | | | | | |
Collapse
|
28
|
Rahomäki J, Nuutinen T, Karvonen L, Honkanen S, Vahimaa P. Horizontal slot waveguide channel for enhanced Raman scattering. OPTICS EXPRESS 2013; 21:9060-9068. [PMID: 23571995 DOI: 10.1364/oe.21.009060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Herein we characterize and experimentally demonstrate a new type of a horizontal slot waveguide structure for remarkably enhanced Raman scattering detection in nanometer-scale void channels. As the measurement sensitivity is one of the key limiting factors in nanofluidic detection, it is essential to search advanced solutions for such detection. Combining an all dielectric resonance waveguide grating and a surface enhanced Raman scattering (SERS) substrate in a close proximity it is possible to create high electromagnetic field energy hot zones within an adjustable slot region. This results in a strong enhancement in Raman scattering. We show the theoretical principles and demonstrate, with rhodamine 6G molecules, an approximately 20-fold enhancement compared to a conventional SERS substrate within the corresponding slot arrangement. We foresee potential applications for the proposed approach in the fields of medical, biological and chemical sensing, where the high detection sensitivity is essential due to integration with nanofluidic devices.
Collapse
Affiliation(s)
- Jussi Rahomäki
- University of Eastern Finland, Department of Physics and Mathematics, P.O. Box 111, 80101 Joensuu, Finland.
| | | | | | | | | |
Collapse
|
29
|
Effects of Micromachining Processes on Electro-Osmotic Flow Mobility of Glass Surfaces. MICROMACHINES 2013. [DOI: 10.3390/mi4010067] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
|
30
|
Pang L, Chen HM, Freeman LM, Fainman Y. Optofluidic devices and applications in photonics, sensing and imaging. LAB ON A CHIP 2012; 12:3543-3551. [PMID: 22810383 DOI: 10.1039/c2lc40467b] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Optofluidics integrates the fields of photonics and microfluidics, providing new freedom to both fields and permitting the realization of optical and fluidic property manipulations at the chip scale. Optofluidics was formed only after many breakthroughs in microfluidics, as understanding of fluid behaviour at the micron level enabled researchers to combine the advantages of optics and fluids. This review describes the progress of optofluidics from a photonics perspective, highlighting various optofluidic aspects ranging from the device's property manipulation to an interactive integration between optics and fluids. First, we describe photonic elements based on the functionalities that enable fluid manipulation. We then discuss the applications of optofluidic biodetection with an emphasis on nanosensing. Next, we discuss the progress of optofluidic lenses with an emphasis on its various architectures, and finally we conceptualize on where the field may lead.
Collapse
Affiliation(s)
- Lin Pang
- Jacobs School of Engineering, University of California, La Jolla, San Diego, California 92093-0407, USA.
| | | | | | | |
Collapse
|
31
|
Threm D, Nazirizadeh Y, Gerken M. Photonic crystal biosensors towards on-chip integration. JOURNAL OF BIOPHOTONICS 2012; 5:601-616. [PMID: 22678992 DOI: 10.1002/jbio.201200039] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 04/24/2012] [Accepted: 05/02/2012] [Indexed: 06/01/2023]
Abstract
Photonic crystal technology has attracted large interest in the last years. The possibility to generate highly sensitive sensor elements with photonic crystal structures is very promising for medical or environmental applications. The low-cost fabrication on the mass scale is as advantageous as the compactness and reliability of photonic crystal biosensors. The possibility to integrate microfluidic channels together with photonic crystal structures allows for highly compact devices. This article reviews different types of photonic crystal sensors including 1D photonic crystal biosensors, biosensors with photonic crystal slabs, photonic crystal waveguide biosensors and biosensors with photonic crystal microcavities. Their applications in biomolecular and pathogen detection are highlighted. The sensitivities and the detection limits of the different biosensors are compared. The focus is on the possibilities to integrate photonic crystal biosensors on-chip.
Collapse
Affiliation(s)
- Daniela Threm
- Institute of Electrical and Information Engineering, Christian-Albrechts-Universität zu Kiel, Kiel, Germany.
| | | | | |
Collapse
|
32
|
Grepstad JO, Kaspar P, Solgaard O, Johansen IR, Sudbø AS. Photonic-crystal membranes for optical detection of single nano-particles, designed for biosensor application. OPTICS EXPRESS 2012; 20:7954-7965. [PMID: 22453468 DOI: 10.1364/oe.20.007954] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A sensor designed to detect bio-molecules is presented. The sensor exploits a planar 2D photonic crystal (PC) membrane with sub-micron thickness and through holes, to induce high optical fields that allow detection of nano-particles smaller than the diffraction limit of an optical microscope. We report on our design and fabrication of a PC membrane with a nano-particle trapped inside. We have also designed and built an imaging system where an optical microscope and a CCD camera are used to take images of the PC membrane. Results show how the trapped nano-particle appears as a bright spot in the image. In a first experimental realization of the imaging system, single particles with a radius of 75 nm can be detected.
Collapse
Affiliation(s)
- Jon Olav Grepstad
- Department of Electronics and Telecommunications, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
| | | | | | | | | |
Collapse
|
33
|
Fan X, White IM. Optofluidic Microsystems for Chemical and Biological Analysis. NATURE PHOTONICS 2011; 5:591-597. [PMID: 22059090 PMCID: PMC3207487 DOI: 10.1038/nphoton.2011.206] [Citation(s) in RCA: 406] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Optofluidics - the synergistic integration of photonics and microfluidics - has recently emerged as a new analytical field that provides a number of unique characteristics for enhanced sensing performance and simplification of microsystems. In this review, we describe various optofluidic architectures developed in the past five years, emphasize the mechanisms by which optofluidics enhances bio/chemical analysis capabilities, including sensing and the precise control of biological micro/nanoparticles, and envision new research directions to which optofluidics leads.
Collapse
Affiliation(s)
- Xudong Fan
- Biomedical Engineering Department, University of Michigan, Ann Arbor, MI 48109, USA
| | | |
Collapse
|
34
|
Turkmen M, Aksu S, Çetin AE, Yanik AA, Altug H. Multi-resonant metamaterials based on UT-shaped nano-aperture antennas. OPTICS EXPRESS 2011; 19:7921-8. [PMID: 21503104 DOI: 10.1364/oe.19.007921] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
We demonstrate a compact multi-resonant metamaterial structure based on integrated U- and T-shaped nano-aperture antennas. We investigate the physical origin of the multi-resonant behavior and determine the parameter dependence of the nano-aperture antennas both experimentally and numerically. We also show enhanced field distribution in the apertures at the corresponding resonance wavelengths. Both multi-spectral response and enhanced near field distributions can open up exciting new opportunities in applications ranging from subwavelength optics and optoelectronics to chemical and biosensing.
Collapse
Affiliation(s)
- Mustafa Turkmen
- Electrical and Electronics Engineering, Erciyes University, 38039, Kayseri, Turkey
| | | | | | | | | |
Collapse
|
35
|
Yanik AA, Huang M, Kamohara O, Artar A, Geisbert TW, Connor JH, Altug H. An optofluidic nanoplasmonic biosensor for direct detection of live viruses from biological media. NANO LETTERS 2010; 10:4962-9. [PMID: 21053965 PMCID: PMC3123676 DOI: 10.1021/nl103025u] [Citation(s) in RCA: 224] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Fast and sensitive virus detection techniques, which can be rapidly deployed at multiple sites, are essential to prevent and control future epidemics and bioterrorism threats. In this Letter, we demonstrate a label-free optofluidic nanoplasmonic sensor that can directly detect intact viruses from biological media at clinically relevant concentrations with little to no sample preparation. Our sensing platform is based on an extraordinary light transmission effect in plasmonic nanoholes and utilizes group-specific antibodies for highly divergent strains of rapidly evolving viruses. So far, the questions remain for the possible limitations of this technique for virus detection, as the penetration depths of the surface plasmon polaritons are comparable to the dimensions of the pathogens. Here, we demonstrate detection and recognition of small enveloped RNA viruses (vesicular stomatitis virus and pseudotyped Ebola) as well as large enveloped DNA viruses (vaccinia virus) within a dynamic range spanning 3 orders of magnitude. Our platform, by enabling high signal to noise measurements without any mechanical or optical isolation, opens up opportunities for detection of a broad range of pathogens in typical biology laboratory settings.
Collapse
Affiliation(s)
- Ahmet A. Yanik
- Photonics Center, Boston University, Boston, MA, 02215
- Electrical and Computer Engineering, Boston University, Boston, MA, 02215
| | - Min Huang
- Photonics Center, Boston University, Boston, MA, 02215
- Electrical and Computer Engineering, Boston University, Boston, MA, 02215
| | - Osami Kamohara
- Photonics Center, Boston University, Boston, MA, 02215
- Electrical and Computer Engineering, Boston University, Boston, MA, 02215
| | - Alp Artar
- Photonics Center, Boston University, Boston, MA, 02215
- Electrical and Computer Engineering, Boston University, Boston, MA, 02215
| | - Thomas W. Geisbert
- The National Emerging Infectious Diseases Laboratories (NEIDL), Boston University School of Medicine, Boston, MA, 02218
- Department of Microbiology, Boston University School of Medicine, Boston, MA, 02218
| | - John H. Connor
- Department of Microbiology, Boston University School of Medicine, Boston, MA, 02218
| | - Hatice Altug
- Photonics Center, Boston University, Boston, MA, 02215
- Electrical and Computer Engineering, Boston University, Boston, MA, 02215
| |
Collapse
|
36
|
El Beheiry M, Liu V, Fan S, Levi O. Sensitivity enhancement in photonic crystal slab biosensors. OPTICS EXPRESS 2010; 18:22702-14. [PMID: 21164609 DOI: 10.1364/oe.18.022702] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Refractive index sensitivity of guided resonances in photonic crystal slabs is analyzed. We show that modal properties of guided resonances strongly affect spectral sensitivity and quality factors, resulting in substantial enhancement of refractive index sensitivity. A three-fold spectral sensitivity enhancement is demonstrated for suspended slab designs, in contrast to designs with a slab resting over a substrate. Spectral sensitivity values are additionally shown to be unaffected by quality factor reductions, which are common to fabricated photonic crystal nano-structures. Finally, we determine that proper selection of photonic crystal slab design parameters permits biosensing of a wide range of analytes, including proteins, antigens, and cells. These photonic crystals are compatible with large-area biosensor designs, permitting direct access to externally incident optical beams in a microfluidic device.
Collapse
Affiliation(s)
- Mohamed El Beheiry
- The Edward S Rogers Sr Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario M5S 3G4, Canada
| | | | | | | |
Collapse
|
37
|
Hallynck E, Bienstman P. Photonic crystal biosensor based on angular spectrum analysis. OPTICS EXPRESS 2010; 18:18164-18170. [PMID: 20721205 DOI: 10.1364/oe.18.018164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The need for cost effective and reliable biosensors in e.g. medical applications is an ever growing and everlasting one. Not only do we strive to increase sensitivity and detection limit of such sensors; ease of fabrication or implementation are equally important. In this work, we propose a novel, photonic crystal based biosensor that is able to operate at a single frequency, contrary to resonance based sensors. In a certain frequency range, guided photonic crystal modes can couple to free space modes resulting in a Lorentzian shape in the angular spectrum. This Lorentzian can shift due to refractive index changes and simulations have shown sensitivities of 65 degrees per refractive index unit and more.
Collapse
Affiliation(s)
- Elewout Hallynck
- Photonics Research Group, Department of Information Technology, Ghent University-imec, Sint-Pietersnieuwstraat 41, 9000 Gent, Belgium.
| | | |
Collapse
|
38
|
Pisco M, Ricciardi A, Gallina I, Castaldi G, Campopiano S, Cutolo A, Cusano A, Galdi V. Tuning efficiency and sensitivity of guided resonances in photonic crystals and quasi-crystals: a comparative study. OPTICS EXPRESS 2010; 18:17280-93. [PMID: 20721116 DOI: 10.1364/oe.18.017280] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
In this paper, we present a comparative study of the tuning efficiency and sensitivity of guided resonances (GRs) in photonic crystal (PC) holed slabs based on periodic and aperiodically-ordered unit cells, aimed at assessing the applicability of these important technology platforms to ultra-compact optical sensors and active devices. In particular, with specific reference to square-lattice periodic PCs and aperiodically-ordered Ammann-Beenker photonic quasi-crystals, we study the effects of the hole radius, slab thickness, and refractive index on the GR sensitivity and tunability with respect to variation in the hole refractive index. Finally, we carry out a theoretical and numerical analysis in order to correlate the GR shift with the field distribution of the unperturbed (air holes) structures. Our results indicate that the spatial arrangement of the holes may strongly influence the tuning and sensitivity efficiency, and may provide new degrees of freedom and tools for the design and optimization of novel photonic devices for both sensing and telecommunication applications.
Collapse
Affiliation(s)
- Marco Pisco
- Optoelectronic Division, Dept of Engineering, University of Sannio, Corso Garibaldi 107, I-82100 Benevento, Italy
| | | | | | | | | | | | | | | |
Collapse
|
39
|
Aksu S, Yanik AA, Adato R, Artar A, Huang M, Altug H. High-throughput nanofabrication of infrared plasmonic nanoantenna arrays for vibrational nanospectroscopy. NANO LETTERS 2010; 10:2511-8. [PMID: 20560536 DOI: 10.1021/nl101042a] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The introduction of high-throughput and high-resolution nanofabrication techniques operating at low cost and low complexity is essential for the advancement of nanoplasmonic and nanophotonic fields. In this paper, we demonstrate a novel fabrication approach based on nanostencil lithography for high-throughput fabrication of engineered infrared plasmonic nanorod antenna arrays. The technique relying on deposition of materials through a shadow mask enables plasmonic substrates supporting spectrally sharp collective resonances. We show that reflectance spectra of these antenna arrays are comparable to that of arrays fabricated by electron beam lithography. We also show that nanostencils can be reused multiple times to fabricate a series of infrared nanoantenna arrays with identical optical responses. Finally, we demonstrate fabrication of plasmonic nanostructures in a variety of shapes with a single metal deposition step on different substrates, including nonconducting ones. Our approach, by enabling the reusability of the stencil and offering flexibility on the substrate choice and nanopattern design, could facilitate the transition of plasmonic technologies to the real-world applications.
Collapse
Affiliation(s)
- Serap Aksu
- Materials Science and Engineering, Boston University, Boston, Massachusetts 02215, USA
| | | | | | | | | | | |
Collapse
|