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Fukuda A, Asano T, Kawakatsu T, Takahashi Y, Noda S. Suppressing the sample-to-sample variation of photonic crystal nanocavity Q-factors by air-hole patterns with broken mirror symmetry. OPTICS EXPRESS 2023; 31:15495-15513. [PMID: 37157650 DOI: 10.1364/oe.488516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
It is known that the quality factors (Q) of photonic crystal nanocavities vary from sample to sample due to air-hole fabrication fluctuations. In other words, for the mass production of a cavity with a given design, we need to consider that the Q can vary significantly. So far, we have studied the sample-to-sample variation in Q for symmetric nanocavity designs, that is, nanocavity designs where the positions of the holes maintain mirror symmetry with respect to both symmetry axes of the nanocavity. Here we investigate the variation of Q for a nanocavity design in which the air-hole pattern has no mirror symmetry (a so-called asymmetric cavity design). First, an asymmetric cavity design with a Q of about 250,000 was developed by machine learning using neural networks, and then we fabricated fifty cavities with the same design. We also fabricated fifty symmetric cavities with a design Q of about 250,000 for comparison. The variation of the measured Q values of the asymmetric cavities was 39% smaller than that of the symmetric cavities. This result is consistent with simulations in which the air-hole positions and radii are randomly varied. Asymmetric nanocavity designs may be useful for mass production since the variation in Q is suppressed.
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Takahashi Y, Fujimoto M, Kikunaga K, Takahashi Y. Detection of ionized air using a photonic-crystal nanocavity excited by broadband light from a superluminescent diode. OPTICS EXPRESS 2022; 30:10694-10708. [PMID: 35473030 DOI: 10.1364/oe.454328] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 03/08/2022] [Indexed: 06/14/2023]
Abstract
It has been shown that silicon photonic crystal nanocavities excited by spectrally narrow light can be used to detect ionized air. Here, to increase the range of possible applications of nanocavity-based sensing, the use of broadband light is considered. We find that the use of a superluminescent diode (SLD) as an excitation source enables a more reproducible detection of ionized air. When our photonic-crystal nanocavity is exposed to ionized air, carriers are transferred to the cavity and the light emission from the cavity decreases due to free carrier absorption. Owing to the broadband light source, the resonance wavelength shifts caused by the carriers in this system (for example, due to temperature fluctuations) do not influence the emission intensity. SLD-excited cavities could be useful to determine the density of ions in air quantitatively.
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Hempel M, Schroeder V, Park C, Koman VB, Xue M, McVay E, Spector S, Dubey M, Strano MS, Park J, Kong J, Palacios T. SynCells: A 60 × 60 μm 2 Electronic Platform with Remote Actuation for Sensing Applications in Constrained Environments. ACS NANO 2021; 15:8803-8812. [PMID: 33960771 DOI: 10.1021/acsnano.1c01259] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Autonomous electronic microsystems smaller than the diameter of a human hair (<100 μm) are promising for sensing in confined spaces such as microfluidic channels or the human body. However, they are difficult to implement due to fabrication challenges and limited power budget. Here we present a 60 × 60 μm electronic microsystem platform, or SynCell, that overcomes these issues by leveraging the integration capabilities of two-dimensional material circuits and the low power consumption of passive germanium timers, memory-like chemical sensors, and magnetic pads. In a proof-of-concept experiment, we magnetically positioned SynCells in a microfluidic channel to detect putrescine. After we extracted them from the channel, we successfully read out the timer and sensor signal, the latter of which can be amplified by an onboard transistor circuit. The concepts developed here will be applicable to microsystems targeting a variety of applications from microfluidic sensing to biomedical research.
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Affiliation(s)
- Marek Hempel
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Vera Schroeder
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Chibeom Park
- Department of Chemistry, Pritzker School of Molecular Engineering, and James Franck Institute, University of Chicago, 5735 S Ellis Avenue, Chicago, Illinois 60637, United States
| | - Volodymyr B Koman
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Mantian Xue
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Elaine McVay
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Sarah Spector
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Madan Dubey
- Sensors and Electron Devices Directorate, U.S. Army Research Laboratory, Adelphi, Maryland 20783, United States
| | - Michael S Strano
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Jiwoong Park
- Department of Chemistry, Pritzker School of Molecular Engineering, and James Franck Institute, University of Chicago, 5735 S Ellis Avenue, Chicago, Illinois 60637, United States
| | - Jing Kong
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Tomás Palacios
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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Kimoto T, Suzuki K, Fukuda T, Emoto A. An on-demand bench-top fabrication process for fluidic chips based on cross-diffusion through photopolymerization. BIOMICROFLUIDICS 2020; 14:044104. [PMID: 32699564 PMCID: PMC7354092 DOI: 10.1063/5.0014956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 06/30/2020] [Indexed: 06/11/2023]
Abstract
In this paper, we propose a novel approach to fabricate fluidic chips. The method utilizes molecular cross-diffusion, induced by photopolymerization under ultraviolet (UV) irradiation in a channel pattern, to form the channel structures. During channel structure formation, the photopolymer layer still contains many uncured molecules. Subsequently, a top substrate is attached to the channel structure under adequate pressure, and the entire chip is homogenously irradiated by UV light. Immediately thereafter, a sufficiently sealed fluidic chip is formed. Using this fabrication process, the channel pattern of a chip can be designed quickly by a computer as binary images, and practical chips can be produced on demand at a benchtop, instead of awaiting production in specialized factories.
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Affiliation(s)
- Takumi Kimoto
- Graduate School of Science and Engineering, Doshisha University, 1-3 Tatara-Miyakodani, Kyotanabe, Kyoto 610-0321, Japan
| | - Kou Suzuki
- Graduate School of Science and Engineering, Doshisha University, 1-3 Tatara-Miyakodani, Kyotanabe, Kyoto 610-0321, Japan
| | - Takashi Fukuda
- Sensing System Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan
| | - Akira Emoto
- Institute of Post-LED Photonics (pLED), Tokushima University, 2-1 Minami-Josanjima, Tokushima, Tokushima 770-8506, Japan
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