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Li Y, Zhang H, Li Q, Deng Y, Ye Z, Gui L. Texture-structure-based liquid metal filling for blind-end microchannels and its application on multi-layer chips. RSC Adv 2023; 13:24228-24236. [PMID: 37583671 PMCID: PMC10424060 DOI: 10.1039/d3ra04497a] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 08/04/2023] [Indexed: 08/17/2023] Open
Abstract
This research work reports a novel method to achieve fast liquid metal (LM) injection in blind-end microchannels which is especially suitable for multi-layer microfluidic chips. This method is based on a texture-like surface bonding technology. The texture-like surface is fabricated on a polydimethylsiloxane (PDMS) slab with standard soft-lithography technology and bonded with another PDMS slab with microelectrode patterns on it. When injected with LM, the texture-like structure can prevent the LM from entering but allows the air inside to be released during the injection to achieve perfect blind-end complex LM electrodes. The experimental results show that it can achieve fast and perfect LM injection in the blind-end pattern and can also prevent the large area of the flat chamber from collapsing during bonding. We also parametrically studied the texture structure's size for bonding strength between the texture structure and the blank PDMS surface. In addition, we integrate three layers of blind-end complex liquid metal patterns into one multi-layer chip using this technology and later use this structure to realize series connection of two LM-based electroosmotic micropumps (EOP). Compared with the conventional LM-based EOP, the structure of the EOP chip was greatly simplified and resulted in a higher level of integration.
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Affiliation(s)
- Yuqing Li
- Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences 29 Zhongguancun East Road, Haidian District Beijing 100190 China
- School of Future Technology, University of Chinese Academy of Sciences Beijing 10039 China
| | - Huimin Zhang
- Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences 29 Zhongguancun East Road, Haidian District Beijing 100190 China
- School of Engineering Science, University of Chinese Academy of Sciences Beijing 10039 China
| | - Qian Li
- Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences 29 Zhongguancun East Road, Haidian District Beijing 100190 China
- School of Engineering Science, University of Chinese Academy of Sciences Beijing 10039 China
| | - Yuqin Deng
- Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences 29 Zhongguancun East Road, Haidian District Beijing 100190 China
- School of Future Technology, University of Chinese Academy of Sciences Beijing 10039 China
| | - Zi Ye
- Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences 29 Zhongguancun East Road, Haidian District Beijing 100190 China
| | - Lin Gui
- Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences 29 Zhongguancun East Road, Haidian District Beijing 100190 China
- School of Future Technology, University of Chinese Academy of Sciences Beijing 10039 China
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2
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Wu J, Fang H, Zhang J, Yan S. Modular microfluidics for life sciences. J Nanobiotechnology 2023; 21:85. [PMID: 36906553 PMCID: PMC10008080 DOI: 10.1186/s12951-023-01846-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 03/06/2023] [Indexed: 03/13/2023] Open
Abstract
The advancement of microfluidics has enabled numerous discoveries and technologies in life sciences. However, due to the lack of industry standards and configurability, the design and fabrication of microfluidic devices require highly skilled technicians. The diversity of microfluidic devices discourages biologists and chemists from applying this technique in their laboratories. Modular microfluidics, which integrates the standardized microfluidic modules into a whole, complex platform, brings the capability of configurability to conventional microfluidics. The exciting features, including portability, on-site deployability, and high customization motivate us to review the state-of-the-art modular microfluidics and discuss future perspectives. In this review, we first introduce the working mechanisms of the basic microfluidic modules and evaluate their feasibility as modular microfluidic components. Next, we explain the connection approaches among these microfluidic modules, and summarize the advantages of modular microfluidics over integrated microfluidics in biological applications. Finally, we discuss the challenge and future perspectives of modular microfluidics.
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Affiliation(s)
- Jialin Wu
- Institute for Advanced Study, Shenzhen University, Shenzhen, 518060, China
- Nanophotonics Research Center, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen, China
| | - Hui Fang
- Nanophotonics Research Center, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen, China
| | - Jun Zhang
- Queensland Micro and Nanotechnology Centre, Griffith University, Brisbane, QLD, 4111, Australia
| | - Sheng Yan
- Institute for Advanced Study, Shenzhen University, Shenzhen, 518060, China.
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3
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Deep Learning-Assisted Droplet Digital PCR for Quantitative Detection of Human Coronavirus. BIOCHIP JOURNAL 2023; 17:112-119. [PMID: 36687365 PMCID: PMC9843095 DOI: 10.1007/s13206-023-00095-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Revised: 11/15/2022] [Accepted: 12/29/2022] [Indexed: 01/19/2023]
Abstract
Since coronavirus disease 2019 (COVID-19) pandemic rapidly spread worldwide, there is an urgent demand for accurate and suitable nucleic acid detection technology. Although the conventional threshold-based algorithms have been used for processing images of droplet digital polymerase chain reaction (ddPCR), there are still challenges from noise and irregular size of droplets. Here, we present a combined method of the mask region convolutional neural network (Mask R-CNN)-based image detection algorithm and Gaussian mixture model (GMM)-based thresholding algorithm. This novel approach significantly reduces false detection rate and achieves highly accurate prediction model in a ddPCR image processing. We demonstrated that how deep learning improved the overall performance in a ddPCR image processing. Therefore, our study could be a promising method in nucleic acid detection technology.
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4
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Kerk YJ, Jameel A, Xing X, Zhang C. Recent advances of integrated microfluidic suspension cell culture system. ENGINEERING BIOLOGY 2021; 5:103-119. [PMID: 36970555 PMCID: PMC9996741 DOI: 10.1049/enb2.12015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 09/29/2021] [Accepted: 09/30/2021] [Indexed: 11/19/2022] Open
Abstract
Microfluidic devices with superior microscale fluid manipulation ability and large integration flexibility offer great advantages of high throughput, parallelisation and multifunctional automation. Such features have been extensively utilised to facilitate cell culture processes such as cell capturing and culturing under controllable and monitored conditions for cell-based assays. Incorporating functional components and microfabricated configurations offered different levels of fluid control and cell manipulation strategies to meet diverse culture demands. This review will discuss the advances of single-phase flow and droplet-based integrated microfluidic suspension cell culture systems and their applications for accelerated bioprocess development, high-throughput cell selection, drug screening and scientific research to insight cell biology. Challenges and future prospects for this dynamically developing field are also highlighted.
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Affiliation(s)
- Yi Jing Kerk
- Institute of Biochemical EngineeringDepartment of Chemical Engineering, Tsinghua UniversityBeijingChina
| | - Aysha Jameel
- Institute of Biochemical EngineeringDepartment of Chemical Engineering, Tsinghua UniversityBeijingChina
- MOE Key Laboratory of Industrial BiocatalysisDepartment of Chemical Engineering, Tsinghua UniversityBeijingChina
| | - Xin‐Hui Xing
- Institute of Biochemical EngineeringDepartment of Chemical Engineering, Tsinghua UniversityBeijingChina
- MOE Key Laboratory of Industrial BiocatalysisDepartment of Chemical Engineering, Tsinghua UniversityBeijingChina
- Center for Synthetic and Systems BiologyTsinghua UniversityBeijingChina
| | - Chong Zhang
- Institute of Biochemical EngineeringDepartment of Chemical Engineering, Tsinghua UniversityBeijingChina
- MOE Key Laboratory of Industrial BiocatalysisDepartment of Chemical Engineering, Tsinghua UniversityBeijingChina
- Center for Synthetic and Systems BiologyTsinghua UniversityBeijingChina
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5
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Shi N, Mohibullah M, Easley CJ. Active Flow Control and Dynamic Analysis in Droplet Microfluidics. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2021; 14:133-153. [PMID: 33979546 PMCID: PMC8956363 DOI: 10.1146/annurev-anchem-122120-042627] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Droplet-based microfluidics has emerged as an important subfield within the microfluidic and general analytical communities. Indeed, several unique applications such as digital assay readout and single-cell sequencing now have commercial systems based on droplet microfluidics. Yet there remains room for this research area to grow. To date, most analytical readouts are optical in nature, relatively few studies have integrated sample preparation, and passive means for droplet formation and manipulation have dominated the field. Analytical scientists continue to expand capabilities by developing droplet-compatible method adaptations, for example, by interfacing to mass spectrometers or automating droplet sampling for temporally resolved analysis. In this review, we highlight recently developed fluidic control techniques and unique integrations of analytical methodology with droplet microfluidics-focusing on automation and the connections to analog/digital domains-and we conclude by offering a perspective on current challenges and future applications.
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Affiliation(s)
- Nan Shi
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, USA;
| | - Md Mohibullah
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, USA;
| | - Christopher J Easley
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, USA;
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6
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Fatehifar M, Revell A, Jabbari M. Non-Newtonian Droplet Generation in a Cross-Junction Microfluidic Channel. Polymers (Basel) 2021; 13:1915. [PMID: 34207574 PMCID: PMC8226625 DOI: 10.3390/polym13121915] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 06/03/2021] [Accepted: 06/07/2021] [Indexed: 01/10/2023] Open
Abstract
A two-dimensional CFD model based on volume-of-fluid (VOF) is introduced to examine droplet generation in a cross-junction microfluidic using an open-source software, OpenFOAM together with an interFoam solver. Non-Newtonian power-law droplets in Newtonian liquid is numerically studied and its effect on droplet size and detachment time in three different regimes, i.e., squeezing, dripping and jetting, are investigated. To understand the droplet formation mechanism, the shear-thinning behaviour was enhanced by increasing the polymer concentrations in the dispersed phase. It is observed that by choosing a shear-dependent fluid, droplet size decreases compared to Newtonian fluids while detachment time increases due to higher apparent viscosity. Moreover, the rheological parameters-n and K in the power-law model-impose a considerable effect on the droplet size and detachment time, especially in the dripping and jetting regimes. Those parameters also have the potential to change the formation regime if the capillary number (Ca) is high enough. This work extends the understanding of non-Newtonian droplet formation in microfluidics to control the droplet characteristics in applications involving shear-thinning polymeric solutions.
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Affiliation(s)
| | | | - Masoud Jabbari
- Department of Mechanical, Aerospace and Civil Engineering, The University of Manchester, Manchester M13 9PL, UK; (M.F.); (A.R.)
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Li D, Cao Y, Huang B, Han M, Wu X, Sun Q, Zheng C, Zhao L, Ma C, Jin H, Wang X, Liu Y, Zhang Y. Active Femtoliter Droplet Generation in Microfluidics by Confined Interface Vibration. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:1297-1305. [PMID: 33428403 DOI: 10.1021/acs.langmuir.0c03368] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The precise and effective generation of micron-sized droplets is one of the most common and important issues for droplet-based microfluidics. Active droplet generation makes use of additional energy input in promoting interfacial instabilities for droplet generation. Here, we report a new technique for the active generation of femtoliter droplets in microfluidic systems using confined interfacial vibration (CIV). The CIV is formed at the orifice of a traditional inkjet nozzle first by pushing the liquid out and then pulling it back. Droplets are pinched off during the withdrawal process, and this is different from the current active droplet generation techniques, which only monodirectionally push the liquid out. Droplets with radius ranging from ca. 1 to 28 μm can be actively generated by CIV at an orifice with radius 30 μm, distinguishing from conventional active generation techniques in which the droplets are always comparable or slightly bigger than the orifice. Experimental results showed that the droplet volume can be customized by controlling the intensity of the CIV. The inherent digital nature of the inkjet technique enables easy and precise regulating of the droplet volume, making it seamlessly compatible with the digital microfluidic systems.
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Affiliation(s)
- Dege Li
- College of Mechanical and Electronic Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Yi Cao
- College of Mechanical and Electronic Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Bingfang Huang
- College of Mechanical and Electronic Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Molong Han
- Centre of Micro-photonics, Swinburne University of Technology, Melbourne 3122, Australia
| | - Xinlei Wu
- College of Mechanical and Electronic Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Qiang Sun
- College of Mechanical and Electronic Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Chao Zheng
- Department of Chemical and Process Engineering, University of Surrey, Guildford GU2 7XH, U.K
| | - Lilong Zhao
- College of Mechanical and Electronic Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Chi Ma
- College of Mechanical and Electronic Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Hui Jin
- College of Mechanical and Electronic Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Xiaolong Wang
- Dongying Science and Technology Bureau, Dongying 257000, China
| | - Yonghong Liu
- College of Mechanical and Electronic Engineering, China University of Petroleum (East China), Qingdao 266580, China
| | - Yanzhen Zhang
- College of Mechanical and Electronic Engineering, China University of Petroleum (East China), Qingdao 266580, China
- Centre of Micro-photonics, Swinburne University of Technology, Melbourne 3122, Australia
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8
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Programmable µChopper Device with On-Chip Droplet Mergers for Continuous Assay Calibration. MICROMACHINES 2020; 11:mi11060620. [PMID: 32630555 PMCID: PMC7344876 DOI: 10.3390/mi11060620] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 06/18/2020] [Accepted: 06/22/2020] [Indexed: 12/21/2022]
Abstract
While droplet-based microfluidics is a powerful technique with transformative applications, most devices are passively operated and thus have limited real-time control over droplet contents. In this report, an automated droplet-based microfluidic device with pneumatic pumps and salt water electrodes was developed to generate and coalesce up to six aqueous-in-oil droplets (2.77 nL each). Custom control software combined six droplets drawn from any of four inlet reservoirs. Using our μChopper method for lock-in fluorescence detection, we first accomplished continuous linear calibration and quantified an unknown sample. Analyte-independent signal drifts and even an abrupt decrease in excitation light intensity were corrected in real-time. The system was then validated with homogeneous insulin immunoassays that showed a nonlinear response. On-chip droplet merging with antibody-oligonucleotide (Ab-oligo) probes, insulin standards, and buffer permitted the real-time calibration and correction of large signal drifts. Full calibrations (LODconc = 2 ng mL−1 = 300 pM; LODamt = 5 amol) required <1 min with merely 13.85 nL of Ab-oligo reagents, giving cost-savings 160-fold over the standard well-plate format while also automating the workflow. This proof-of-concept device—effectively a microfluidic digital-to-analog converter—is readily scalable to more droplets, and it is well-suited for the real-time automation of bioassays that call for expensive reagents.
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9
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Yu Z, Lyu W, Yu M, Wang Q, Qu H, Ismagilov RF, Han X, Lai D, Shen F. Self-partitioning SlipChip for slip-induced droplet formation and human papillomavirus viral load quantification with digital LAMP. Biosens Bioelectron 2020; 155:112107. [DOI: 10.1016/j.bios.2020.112107] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 02/05/2020] [Accepted: 02/17/2020] [Indexed: 01/20/2023]
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10
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Teo AJT, Tan SH, Nguyen NT. On-Demand Droplet Merging with an AC Electric Field for Multiple-Volume Droplet Generation. Anal Chem 2020; 92:1147-1153. [PMID: 31763821 DOI: 10.1021/acs.analchem.9b04219] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
We introduce a unique system to achieve on-demand droplet merging and splitting using a perpendicular AC electric field. The working mechanism involves a micropillar to split droplets, followed by electrocoalescence using an AC electric field. Adjusting the parameters of the AC signal and conductivity of the fluid result in different merging regimes. We observed a minimum threshold voltage and a strong influence of the surfactant. We hypothesize that the merging process is caused by dipole-dipole coalescence between the daughter droplets. At the same time, adjustment of the conductivity reveals a shift in the merging regimes and can be explained with an electric circuit diagram. Size-based sorting using this merging phenomenon is subsequently demonstrated, where alternate, single, double, and triple droplets sorting were achieved. The concept presented in this paper is potentially useful for drug dispensing or multivolume digital polymerase chain reaction, as droplets of multiple sizes can be generated simultaneously.
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Affiliation(s)
- Adrian J T Teo
- Queensland Micro- and Nanotechnology Centre , Griffith University , 170 Kessels Road Queensland 4111 , Brisbane , Australia
| | - Say Hwa Tan
- Queensland Micro- and Nanotechnology Centre , Griffith University , 170 Kessels Road Queensland 4111 , Brisbane , Australia
| | - Nam-Trung Nguyen
- Queensland Micro- and Nanotechnology Centre , Griffith University , 170 Kessels Road Queensland 4111 , Brisbane , Australia
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11
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Spotts I, Leclerc CA, Collier CM. Scalable optical annealing of microfluidic droplets via whispering gallery mode geometry and infrared illumination. APPLIED OPTICS 2019; 58:7904-7908. [PMID: 31674479 DOI: 10.1364/ao.58.007904] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 09/05/2019] [Indexed: 06/10/2023]
Abstract
This work presents a solution to limitations on scalability in traditional on-chip optofluidic polymerase chain reaction (PCR) methods that are based on infrared annealing and droplet-based microfluidics. The scalability in these PCR optofluidic methods is limited by the optical penetration depth of light in a fluid droplet. Traditionally, such an implementation has minimal absorption when the droplet diameter is scaled well below the optical penetration depth due to the small interaction length. In the presented whispering gallery mode (WGM) optofluidic method, a WGM wave is created through total internal reflection, where light is trapped within a droplet. The effect of the trapped light can extend the interaction length beyond the penetration depth, even for small diameter droplets. Thus, this WGM wave permits the use of droplets with diameters scaled below the penetration depth of the light. A theoretical analysis of traditional optical annealing and of the WGM optofluidic method is conducted using finite-difference time-domain analyses. The WGM wave optofluidic method is also demonstrated experimentally, providing higher annealing temperatures than traditional optical annealing. It is envisioned that the presented work will allow for scalable PCR devices implemented on-chip.
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12
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Li X, Hu J, Easley CJ. Automated microfluidic droplet sampling with integrated, mix-and-read immunoassays to resolve endocrine tissue secretion dynamics. LAB ON A CHIP 2018; 18:2926-2935. [PMID: 30112543 PMCID: PMC6234046 DOI: 10.1039/c8lc00616d] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
A fully automated droplet generation and analysis device based on pressure driven push-up valves for precise pumping of fluid and volumetric metering has been developed for high resolution hormone secretion sampling and measurement. The device consists of a 3D-printer templated reservoir for single cells or single tissue culturing, a Y-shaped channel for reagents and sample mixing, a T-junction channel for droplet formation, a reference channel to overcome drifts in fluorescence signal, and a long droplet storage channel allowing incubation for homogeneous immunoassays. The droplets were made by alternating peristaltic pumping of aqueous and oil phases. Device operation was automated, giving precise control over several droplet parameters such as size, oil spacing, and ratio of sample and reference droplets. By integrating an antibody-oligonucleotide based homogeneous immunoassay on-chip, high resolution temporal sampling into droplets was combined with separation-free quantification of insulin secretion from single islets of Langerhans using direct optical readout from the droplets. Quantitative assays of glucose-stimulated insulin secretion were demonstrated at 15 second temporal resolution while detecting as low as 10 amol per droplet, revealing fast insulin oscillations that mirror well-known intracellular calcium signals. This droplet sampling and direct optical analysis approach effectively digitizes the secretory time record from cells into droplets, and the system should be generalizable to a variety of cells and tissue types.
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Affiliation(s)
- Xiangpeng Li
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849, USA.
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13
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Strike Z, Ghofrani K, Backhouse C. CO₂ Laser-Based Rapid Prototyping of Micropumps. MICROMACHINES 2018; 9:mi9050215. [PMID: 30424149 PMCID: PMC6187535 DOI: 10.3390/mi9050215] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 04/25/2018] [Accepted: 04/27/2018] [Indexed: 02/03/2023]
Abstract
The fabrication of microdevices for fluidic control often requires the use of flexible diaphragms in a way that requires cleanroom equipment and compromises performance. We use a CO2 laser to perform the standard ablative techniques of cutting and engraving materials, but we also apply a method that we call laser placement. This allows us to fabricate precisely-positioned and precisely-sized, isolated diaphragms. This in turn enables the rapid prototyping of integrated multilayer microfluidic devices to form complex structures without the need for manual positioning or cleanroom equipment. The fabrication process is also remarkably rapid and capable of being scaled to manufacturing levels of production. We explore the use of these devices to construct a compact system of peristaltic pumps that can form water in oil droplets without the use of the non-pulsatile pumping systems typically required. Many devices can be fabricated at a time on a sheet by sheet basis with a fabrication process that, to our knowledge, is the fastest reported to date for devices of this type (requiring only 3 h). Moreover, this system is unusually compact and self-contained.
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Affiliation(s)
- Zachary Strike
- Electrical and Computer Engineering, and Waterloo Institute of Nanotechnology, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
| | - Kamyar Ghofrani
- DropLab Inc., 151 Charles Steet West, Kitchener, ON N2G 1H6, Canada.
| | - Chris Backhouse
- Electrical and Computer Engineering, and Waterloo Institute of Nanotechnology, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
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14
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Wang J, Li Y, Wang X, Wang J, Tian H, Zhao P, Tian Y, Gu Y, Wang L, Wang C. Droplet Microfluidics for the Production of Microparticles and Nanoparticles. MICROMACHINES 2017. [PMCID: PMC6189904 DOI: 10.3390/mi8010022] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Droplet microfluidics technology is recently a highly interesting platform in material fabrication. Droplets can precisely monitor and control entire material fabrication processes and are superior to conventional bulk techniques. Droplet production is controlled by regulating the channel geometry and flow rates of each fluid. The micro-scale size of droplets results in rapid heat and mass-transfer rates. When used as templates, droplets can be used to develop reproducible and scalable microparticles with tailored sizes, shapes and morphologies, which are difficult to obtain using traditional bulk methods. This technology can revolutionize material processing and application platforms. Generally, microparticle preparation methods involve three steps: (1) the formation of micro-droplets using a microfluidics generator; (2) shaping the droplets in micro-channels; and (3) solidifying the droplets to form microparticles. This review discusses the production of microparticles produced by droplet microfluidics according to their morphological categories, which generally determine their physicochemical properties and applications.
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Affiliation(s)
- Jianmei Wang
- School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China;
- Energy Research Institute, Shandong Academy of Sciences, Jinan 250014, China; (Y.L.); (X.W.); (J.W.); (H.T.); (P.Z.)
| | - Yan Li
- Energy Research Institute, Shandong Academy of Sciences, Jinan 250014, China; (Y.L.); (X.W.); (J.W.); (H.T.); (P.Z.)
| | - Xueying Wang
- Energy Research Institute, Shandong Academy of Sciences, Jinan 250014, China; (Y.L.); (X.W.); (J.W.); (H.T.); (P.Z.)
| | - Jianchun Wang
- Energy Research Institute, Shandong Academy of Sciences, Jinan 250014, China; (Y.L.); (X.W.); (J.W.); (H.T.); (P.Z.)
| | - Hanmei Tian
- Energy Research Institute, Shandong Academy of Sciences, Jinan 250014, China; (Y.L.); (X.W.); (J.W.); (H.T.); (P.Z.)
| | - Pei Zhao
- Energy Research Institute, Shandong Academy of Sciences, Jinan 250014, China; (Y.L.); (X.W.); (J.W.); (H.T.); (P.Z.)
| | - Ye Tian
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China;
| | - Yeming Gu
- Shandong Shengli Co., Ltd., Jinan 250101, China;
| | - Liqiu Wang
- Energy Research Institute, Shandong Academy of Sciences, Jinan 250014, China; (Y.L.); (X.W.); (J.W.); (H.T.); (P.Z.)
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China;
- Correspondence: (L.W.); (C.W.); Tel.: +86-531-8872-8326 (L.W.); +86-22-2789-0481 (C.W.)
| | - Chengyang Wang
- School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China;
- Correspondence: (L.W.); (C.W.); Tel.: +86-531-8872-8326 (L.W.); +86-22-2789-0481 (C.W.)
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15
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A Transdermal Measurement Platform Based on Microfluidics. J CHEM-NY 2017. [DOI: 10.1155/2017/9343824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The Franz diffusion cell is one of the most widely used devices to evaluate transdermal drug delivery. However, this static and nonflowing system has some limitations, such as a relatively large solution volume and skin area and the development of gas bubbles during sampling. To overcome these disadvantages, this study provides a proof of concept for miniaturizing models of transdermal delivery by using a microfluidic chip combined with a diffusion cell. The proposed diffusion microchip system requires only 80 μL of sample solution and provides flow circulation. Two model compounds, Coomassie Brilliant Blue G-250 and potassium ferricyanide, were successfully tested for transdermal delivery experiments. The diffusion rate is high for a high sample concentration or a large membrane pore size. The developed diffusion microchip system, which is feasible, can be applied for transdermal measurement in the future.
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16
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Zhu P, Wang L. Passive and active droplet generation with microfluidics: a review. LAB ON A CHIP 2016; 17:34-75. [PMID: 27841886 DOI: 10.1039/c6lc01018k] [Citation(s) in RCA: 495] [Impact Index Per Article: 61.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Precise and effective control of droplet generation is critical for applications of droplet microfluidics ranging from materials synthesis to lab-on-a-chip systems. Methods for droplet generation can be either passive or active, where the former generates droplets without external actuation, and the latter makes use of additional energy input in promoting interfacial instabilities for droplet generation. A unified physical understanding of both passive and active droplet generation is beneficial for effectively developing new techniques meeting various demands arising from applications. Our review of passive approaches focuses on the characteristics and mechanisms of breakup modes of droplet generation occurring in microfluidic cross-flow, co-flow, flow-focusing, and step emulsification configurations. The review of active approaches covers the state-of-the-art techniques employing either external forces from electrical, magnetic and centrifugal fields or methods of modifying intrinsic properties of flows or fluids such as velocity, viscosity, interfacial tension, channel wettability, and fluid density, with a focus on their implementations and actuation mechanisms. Also included in this review is the contrast among different approaches of either passive or active nature.
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Affiliation(s)
- Pingan Zhu
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China. and HKU-Zhejiang Institute of Research and Innovation (HKU-ZIRI), 311300, Hangzhou, Zhejiang, China
| | - Liqiu Wang
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China. and HKU-Zhejiang Institute of Research and Innovation (HKU-ZIRI), 311300, Hangzhou, Zhejiang, China
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17
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Liu WW, Zhu Y, Feng YM, Fang J, Fang Q. Droplet-Based Multivolume Digital Polymerase Chain Reaction by a Surface-Assisted Multifactor Fluid Segmentation Approach. Anal Chem 2016; 89:822-829. [DOI: 10.1021/acs.analchem.6b03687] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Wen-Wen Liu
- Institute of Microanalytical Systems, Department
of Chemistry and Innovation Center for Cell Signaling
Network, Zhejiang University, Hangzhou, 310058, China
| | - Ying Zhu
- Institute of Microanalytical Systems, Department
of Chemistry and Innovation Center for Cell Signaling
Network, Zhejiang University, Hangzhou, 310058, China
| | - Yi-Ming Feng
- Department
of Cell Biology, China Medical University, Shenyang, 110001, China
| | - Jin Fang
- Department
of Cell Biology, China Medical University, Shenyang, 110001, China
| | - Qun Fang
- Institute of Microanalytical Systems, Department
of Chemistry and Innovation Center for Cell Signaling
Network, Zhejiang University, Hangzhou, 310058, China
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18
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19
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Pinch-off of microfluidic droplets with oscillatory velocity of inner phase flow. Sci Rep 2016; 6:31436. [PMID: 27511300 PMCID: PMC4980598 DOI: 10.1038/srep31436] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 07/20/2016] [Indexed: 01/25/2023] Open
Abstract
When one liquid is introduced into another immiscible one, it ultimately fragments due to hydrodynamic instability. In contrast to neck pinch-off without external actuation, the viscous two-fluid system subjected to an oscillatory flow demonstrates higher efficiency in breaking fluid threads. However, the underlying dynamics of this process is less well understood. Here we show that the neck-thinning rate is accelerated by the amplitude of oscillation. By simply evaluating the momentum transfer from external actuation, we derive a dimensionless pre-factor to quantify the accelerated pinch-off. Our data ascribes the acceleration to the non-negligible inner fluid inertia, which neutralizes the inner phase viscous stress that retards the pinch-off. Moreover, we characterize an equivalent neck-thinning behavior between an actuated system and its unactuated counterpart with decreased viscosity ratio. Finally, we demonstrate that oscillation is capable of modulating satellite droplet formation by shifting the pinch-off location. Our study would be useful for manipulating fluids at microscale by external forcing.
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Abstract
Digital PCR (dPCR) is an emerging technology for genetic analysis and clinical diagnostics. To facilitate the widespread application of dPCR, here we developed a new micropatterned superporous absorbent array chip (μSAAC) which consists of an array of microwells packed with highly porous agarose microbeads. The packed beads construct a hierarchically porous microgel which confers superior water adsorption capacity to enable spontaneous filling of PDMS microwells for fluid compartmentalization without the need of sophisticated microfluidic equipment and operation expertise. Using large λ-DNA as the model template, we validated the μSAAC for stochastic partitioning and quantitative digital detection of DNA molecules. Furthermore, as a proof-of-concept, we conducted dPCR detection and single-molecule sequencing of a mutation prevalent in blood cancer, the chromosomal translocation t(14;18), demonstrating the feasibility of the μSAAC for analysis of disease-associated mutations. These experiments were carried out using the standard molecular biology techniques and instruments. Because of its low cost, ease of fabrication, and equipment-free liquid partitioning, the μSAAC is readily adaptable to general lab settings, which could significantly facilitate the widespread application of dPCR technology in basic research and clinical practice.
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Affiliation(s)
- Yazhen Wang
- Department of Chemistry, University of Kansas, Lawrence, KS 66045, USA.
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21
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Collins DJ, Neild A, deMello A, Liu AQ, Ai Y. The Poisson distribution and beyond: methods for microfluidic droplet production and single cell encapsulation. LAB ON A CHIP 2015; 15:3439-59. [PMID: 26226550 DOI: 10.1039/c5lc00614g] [Citation(s) in RCA: 313] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
There is a recognized and growing need for rapid and efficient cell assays, where the size of microfluidic devices lend themselves to the manipulation of cellular populations down to the single cell level. An exceptional way to analyze cells independently is to encapsulate them within aqueous droplets surrounded by an immiscible fluid, so that reagents and reaction products are contained within a controlled microenvironment. Most cell encapsulation work has focused on the development and use of passive methods, where droplets are produced continuously at high rates by pumping fluids from external pressure-driven reservoirs through defined microfluidic geometries. With limited exceptions, the number of cells encapsulated per droplet in these systems is dictated by Poisson statistics, reducing the proportion of droplets that contain the desired number of cells and thus the effective rate at which single cells can be encapsulated. Nevertheless, a number of recently developed actively-controlled droplet production methods present an alternative route to the production of droplets at similar rates and with the potential to improve the efficiency of single-cell encapsulation. In this critical review, we examine both passive and active methods for droplet production and explore how these can be used to deterministically and non-deterministically encapsulate cells.
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Affiliation(s)
- David J Collins
- Engineering Product Design pillar, Singapore University of Technology and Design, Singapore.
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22
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Chen YC, Liu K, Shen CKF, van Dam RM. On-demand generation and mixing of liquid-in-gas slugs with digitally-programmable composition and size. JOURNAL OF MICROMECHANICS AND MICROENGINEERING : STRUCTURES, DEVICES, AND SYSTEMS 2015; 25:084006. [PMID: 29167603 PMCID: PMC5695874 DOI: 10.1088/0960-1317/25/8/084006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Microscopic droplets or slugs of mixed reagents provide a convenient platform for performing large numbers of isolated biochemical or chemical reactions for many screening and optimization applications. Myriad microfluidic approaches have emerged for creating droplets or slugs with controllable size and composition, generally using an immiscible carrier fluid to assist with the formation or merging processes. We report a novel device for generation of liquid slugs in air when the use of a carrier liquid is not compatible with the application. The slug generator contains two adjacent chambers, each of which has a volume that can be digitally adjusted by closing selected microvalves. Reagents are filled into the two chambers, merged together into a contiguous liquid slug, ejected at the desired time from the device using gas pressure, and mixed by flowing in a downstream channel. Programmable size and composition of slugs is achieved by dynamically adjusting the volume of each chamber prior to filling. Slug formation in this fashion is independent of fluid properties and can easily be scaled to mix larger numbers of reagents. This device has already been used to screen monomer ratios in supramolecular nanoparticle assembly and radiolabeling conditions of engineered antibodies, and here we provide a detailed description of the underlying device.
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Affiliation(s)
| | | | - Clifton Kwang-Fu Shen
- Department of Molecular & Medical Pharmacology and Crump Institute for Molecular Imaging, David Geffen School of Medicine, University of California, Los Angeles, 570 Westwood Plaza, Los Angeles, CA 90095
| | - R. Michael van Dam
- Department of Molecular & Medical Pharmacology and Crump Institute for Molecular Imaging, David Geffen School of Medicine, University of California, Los Angeles, 570 Westwood Plaza, Los Angeles, CA 90095
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23
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Hayes CJ, Dalton TM. Microfluidic droplet-based PCR instrumentation for high-throughput gene expression profiling and biomarker discovery. BIOMOLECULAR DETECTION AND QUANTIFICATION 2015; 4:22-32. [PMID: 27077035 PMCID: PMC4822205 DOI: 10.1016/j.bdq.2015.04.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 04/23/2015] [Accepted: 04/24/2015] [Indexed: 01/02/2023]
Abstract
PCR is a common and often indispensable technique used in medical and biological research labs for a variety of applications. Real-time quantitative PCR (RT-qPCR) has become a definitive technique for quantitating differences in gene expression levels between samples. Yet, in spite of this importance, reliable methods to quantitate nucleic acid amounts in a higher throughput remain elusive. In the following paper, a unique design to quantify gene expression levels at the nanoscale in a continuous flow system is presented. Fully automated, high-throughput, low volume amplification of deoxynucleotides (DNA) in a droplet based microfluidic system is described. Unlike some conventional qPCR instrumentation that use integrated fluidic circuits or plate arrays, the instrument performs qPCR in a continuous, micro-droplet flowing process with droplet generation, distinctive reagent mixing, thermal cycling and optical detection platforms all combined on one complete instrument. Detailed experimental profiling of reactions of less than 300 nl total volume is achieved using the platform demonstrating the dynamic range to be 4 order logs and consistent instrument sensitivity. Furthermore, reduced pipetting steps by as much as 90% and a unique degree of hands-free automation makes the analytical possibilities for this instrumentation far reaching. In conclusion, a discussion of the first demonstrations of this approach to perform novel, continuous high-throughput biological screens is presented. The results generated from the instrument, when compared with commercial instrumentation, demonstrate the instrument reliability and robustness to carry out further studies of clinical significance with added throughput and economic benefits.
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Affiliation(s)
- Christopher J Hayes
- Stokes Institute, Department of Mechanical, Aeronautical and Biomedical Engineering, University of Limerick, Limerick, Ireland; Department of Life Sciences, University of Limerick, Limerick, Ireland
| | - Tara M Dalton
- Stokes Institute, Department of Mechanical, Aeronautical and Biomedical Engineering, University of Limerick, Limerick, Ireland
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24
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Ding Y, Casadevall i Solvas X, deMello A. “V-junction”: a novel structure for high-speed generation of bespoke droplet flows. Analyst 2015; 140:414-21. [DOI: 10.1039/c4an01730g] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present the use of microfluidic “V-junctions” as a droplet generation strategy that incorporates enhanced performance characteristics when compared to more traditional “T-junction” formats.
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Affiliation(s)
- Yun Ding
- Department of Chemistry and Applied Biosciences
- Institute for Chemical and Bioengineering
- ETH Zurich
- Zurich
- Switzerland
| | - Xavier Casadevall i Solvas
- Department of Chemistry and Applied Biosciences
- Institute for Chemical and Bioengineering
- ETH Zurich
- Zurich
- Switzerland
| | - Andrew deMello
- Department of Chemistry and Applied Biosciences
- Institute for Chemical and Bioengineering
- ETH Zurich
- Zurich
- Switzerland
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25
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Tangen U, Sharma A, Wagler P, McCaskill JS. On demand nanoliter-scale microfluidic droplet generation, injection, and mixing using a passive microfluidic device. BIOMICROFLUIDICS 2015; 9:014119. [PMID: 25759752 PMCID: PMC4327917 DOI: 10.1063/1.4907895] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 01/29/2015] [Indexed: 05/10/2023]
Abstract
We here present and characterize a programmable nanoliter scale droplet-on-demand device that can be used separately or readily integrated into low cost single layer rapid prototyping microfluidic systems for a wide range of user applications. The passive microfluidic device allows external (off-the-shelf) electronically controlled pinch valves to program the delivery of nanoliter scale aqueous droplets from up to 9 different inputs to a central outlet channel. The inputs can be either continuous aqueous fluid streams or microliter scale aqueous plugs embedded in a carrier fluid, in which case the number of effective input solutions that can be employed in an experiment is no longer strongly constrained (100 s-1000 s). Both nanoliter droplet sequencing output and nanoliter-scale droplet mixing are reported with this device. Optimization of the geometry and pressure relationships in the device was achieved in several hardware iterations with the support of open source microfluidic simulation software and equivalent circuit models. The requisite modular control of pressure relationships within the device is accomplished using hydrodynamic barriers and matched resistance channels with three different channel heights, custom parallel reversible microfluidic I/O connections, low dead-volume pinch valves, and a simply adjustable array of external screw valves. Programmable sequences of droplet mixes or chains of droplets can be achieved with the device at low Hz frequencies, limited by device elasticity, and could be further enhanced by valve integration. The chip has already found use in the characterization of droplet bunching during export and the synthesis of a DNA library.
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Affiliation(s)
- Uwe Tangen
- Faculty of Chemistry and Biochemistry, Microsystems Chemistry and BioIT (BioMIP), Ruhr-University Bochum , 44780 Bochum, Germany
| | - Abhishek Sharma
- Faculty of Chemistry and Biochemistry, Microsystems Chemistry and BioIT (BioMIP), Ruhr-University Bochum , 44780 Bochum, Germany
| | - Patrick Wagler
- Faculty of Chemistry and Biochemistry, Microsystems Chemistry and BioIT (BioMIP), Ruhr-University Bochum , 44780 Bochum, Germany
| | - John S McCaskill
- Faculty of Chemistry and Biochemistry, Microsystems Chemistry and BioIT (BioMIP), Ruhr-University Bochum , 44780 Bochum, Germany
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26
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Abstract
Small-scale pumps will be the heartbeat of many future micro/nanoscale platforms. However, the integration of small-scale pumps is presently hampered by limited flow rate with respect to the input power, and their rather complicated fabrication processes. These issues arise as many conventional pumping effects require intricate moving elements. Here, we demonstrate a system that we call the liquid metal enabled pump, for driving a range of liquids without mechanical moving parts, upon the application of modest electric field. This pump incorporates a droplet of liquid metal, which induces liquid flow at high flow rates, yet with exceptionally low power consumption by electrowetting/deelectrowetting at the metal surface. We present theory explaining this pumping mechanism and show that the operation is fundamentally different from other existing pumps. The presented liquid metal enabled pump is both efficient and simple, and thus has the potential to fundamentally advance the field of microfluidics.
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27
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Culbertson CT, Mickleburgh TG, Stewart-James SA, Sellens KA, Pressnall M. Micro total analysis systems: fundamental advances and biological applications. Anal Chem 2014; 86:95-118. [PMID: 24274655 PMCID: PMC3951881 DOI: 10.1021/ac403688g] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
| | - Tom G. Mickleburgh
- Department of Chemistry, Kansas State University, Manhattan, Kansas 66506, USA
| | | | - Kathleen A. Sellens
- Department of Chemistry, Kansas State University, Manhattan, Kansas 66506, USA
| | - Melissa Pressnall
- Department of Chemistry, Kansas State University, Manhattan, Kansas 66506, USA
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28
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Choi JW, Lee S, Lee DH, Kim J, deMello AJ, Chang SI. Integrated pneumatic micro-pumps for high-throughput droplet-based microfluidics. RSC Adv 2014. [DOI: 10.1039/c4ra02033b] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Droplet-based microfluidic systems have recently emerged as powerful experimental tools in the chemical and biological sciences.
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Affiliation(s)
- Jae-Won Choi
- Department of Biochemistry
- Chungbuk National University
- Cheongju 361-763, Republic of Korea
| | - Sangmin Lee
- Department of Mechanical Engineering
- Pohang University of Science and Technology
- Pohang 790-784, Republic of Korea
| | - Dong-Hun Lee
- Department of Microbiology
- Chungbuk National University
- Cheongju 361-763, Republic of Korea
| | - Joonwon Kim
- Department of Mechanical Engineering
- Pohang University of Science and Technology
- Pohang 790-784, Republic of Korea
| | - Andrew J. deMello
- Department of Chemistry and Applied Biosciences
- ETH Zürich
- Zürich CH-8093, Switzerland
| | - Soo-Ik Chang
- Department of Biochemistry
- Chungbuk National University
- Cheongju 361-763, Republic of Korea
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29
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Wang T, Zhang M, Dreher DD, Zeng Y. Ultrasensitive microfluidic solid-phase ELISA using an actuatable microwell-patterned PDMS chip. LAB ON A CHIP 2013; 13:4190-7. [PMID: 23989677 DOI: 10.1039/c3lc50783a] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Quantitative detection of low abundance proteins is of significant interest for biological and clinical applications. Here we report an integrated microfluidic solid-phase ELISA platform for rapid and ultrasensitive detection of proteins with a wide dynamic range. Compared to the existing microfluidic devices that perform affinity capture and enzyme-based optical detection in a constant channel volume, the key novelty of our design is two-fold. First, our system integrates a microwell-patterned assay chamber that can be pneumatically actuated to significantly reduce the volume of chemifluorescent reaction, markedly improving the sensitivity and speed of ELISA. Second, monolithic integration of on-chip pumps and the actuatable assay chamber allow programmable fluid delivery and effective mixing for rapid and sensitive immunoassays. Ultrasensitive microfluidic ELISA was demonstrated for insulin-like growth factor 1 receptor (IGF-1R) across at least five orders of magnitude with an extremely low detection limit of 21.8 aM. The microwell-based solid-phase ELISA strategy provides an expandable platform for developing the next-generation microfluidic immunoassay systems that integrate and automate digital and analog measurements to further improve the sensitivity, dynamic ranges, and reproducibility of proteomic analysis.
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Affiliation(s)
- Tanyu Wang
- Department of Chemistry, University of Kansas, Lawrence, KS 66045, United States.
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30
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DeJournette CJ, Kim J, Medlen H, Li X, Vincent LJ, Easley CJ. Creating biocompatible oil-water interfaces without synthesis: direct interactions between primary amines and carboxylated perfluorocarbon surfactants. Anal Chem 2013; 85:10556-64. [PMID: 24070333 DOI: 10.1021/ac4026048] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Currently, one of the most prominent methods used to impart biocompatibility to aqueous-in-oil droplets is to synthesize a triblock copolymer surfactant composed of perfluoropolyether and polyether blocks. The resulting surfactants (EA surfactant, KryJeffa, etc.) allow generation of highly biocompatible droplet surfaces while maintaining the heat stability of the starting material. However, production of these surfactants requires expertise in synthetic organic chemistry, creating a barrier to widespread adoption in the field. Herein, we describe a simple alternative to synthetic modification of surfactants to impart biocompatibility. We have observed that aqueous-in-oil droplet surfaces can be made biocompatible and heat stable by merely exploiting binding interactions between polyetherdiamine additives in the aqueous phase and carboxylated perfluorocarbon surfactants in the oil phase. Droplets formed under these conditions are shown to possess biocompatible surfaces capable of supporting picoliter-scale protein assays, droplet polymerase chain reaction (PCR), and droplet DNA amplification with isothermal recombinase polymerase amplification (RPA). Droplets formed with polyetherdiamine aqueous additives are stable enough to withstand temperature cycling during PCR (30-40 cycles at 60-94 °C) while maintaining biocompatibility, and the reaction efficiency of RPA is shown to be similar to that with a covalently modified surfactant (KryJeffa). The binding interaction was confirmed with various methods, including FT-IR spectroscopy, NMR spectroscopy, electrospray ionization mass spectrometry (ESI-MS), and fluorescence microscopy. Overall, our results suggest that, by simply introducing a commercially-available, polyetherdiamine additive (Jeffamine ED-900) to the aqueous phase, researchers can avoid synthetic methods in generating biocompatible droplet surfaces capable of supporting DNA and protein analysis at the subnanoliter scale.
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Affiliation(s)
- Cheryl J DeJournette
- Auburn University , Department of Chemistry and Biochemistry, Auburn, Alabama 36849 United States
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31
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Quantitative microfluidic biomolecular analysis for systems biology and medicine. Anal Bioanal Chem 2013; 405:5743-58. [PMID: 23568613 DOI: 10.1007/s00216-013-6930-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Revised: 03/10/2013] [Accepted: 03/19/2013] [Indexed: 12/12/2022]
Abstract
In the postgenome era, biology and medicine are rapidly evolving towards quantitative and systems studies of complex biological systems. Emerging breakthroughs in microfluidic technologies and innovative applications are transforming systems biology by offering new capabilities to address the challenges in many areas, such as single-cell genomics, gene regulation networks, and pathology. In this review, we focus on recent progress in microfluidic technology from the perspective of its applications to promoting quantitative and systems biomolecular analysis in biology and medicine.
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32
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Almassian DR, Cockrell LM, Nelson WM. Portable nucleic acid thermocyclers. Chem Soc Rev 2013; 42:8769-98. [DOI: 10.1039/c3cs60144g] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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