Multiplexed electrical sensor arrays in microfluidic networks

A major limitation of many microfluidic platforms is their inability to perform large scale, real time, sensing, routing, or scheduling of the materials moving through them. This paper seeks to address the first of these deficiencies by introducing a multiplexed sensing architecture capable of monitoring the movement of liquid droplets in large microfluidic networks. We describe the design and fabrication of the sensor array, as well as its integration and testing in microfluidic networks. Individual sensors consisting of small electrical components (resistors, capacitors, or conduction gaps) are addressed using a multiplexing approach that allows an array of m × n sensors to be supported by only m + n + 1 electrical contacts, as compared to the 2 × m × n contacts traditionally necessary. For example, a multiplexed 10 × 10 array of sensors can be operated with 21 contacts, as opposed to the 200 contacts needed in a traditional configuration. The multiplexing relies on the fact that each sensing element is connected to two electrical leads, and each electrical lead is connected to multiple sensing elements. Here we show the principle using a 4 × 4 multiplexed arrays of resistive and capacitive sensors to monitor the passage of discrete liquid plugs through a microfluidic network.

[1]  F. J. Holler,et al.  Principles of Instrumental Analysis , 1973 .

[2]  S. Gawad,et al.  Micromachined impedance spectroscopy flow cytometer for cell analysis and particle sizing. , 2001, Lab on a chip.

[3]  George M. Whitesides,et al.  Rapid prototyping of complex structures with feature sizes larger than 20 μm , 1996 .

[4]  Jan Lichtenberg,et al.  A microchip electrophoresis system with integrated in‐plane electrodes for contactless conductivity detection , 2002, Electrophoresis.

[5]  Manipulation and real-time electrical detection of individual bacterial cells at electrode junctions: a model for assembly of nanoscale biosystems. , 2005, Nano letters.

[6]  M. Horenstein,et al.  Differential capacitive position sensor for planar MEMS structures with vertical motion , 2000 .

[7]  B. Dai,et al.  A monolithic fabrication process for a micro-flow heat transfer channel suspended over an air layer with arrays of micro-sensors and heaters , 2003 .

[8]  Mark A Burns,et al.  Electronic drop sensing in microfluidic devices: automated operation of a nanoliter viscometer. , 2006, Lab on a Chip.

[9]  Rustem F Ismagilov,et al.  Formation of droplets of alternating composition in microfluidic channels and applications to indexing of concentrations in droplet-based assays. , 2004, Analytical chemistry.

[10]  G. R. Facer,et al.  Capacitance cytometry: measuring biological cells one by one. , 2000, Proceedings of the National Academy of Sciences of the United States of America.

[11]  S. Kulmala,et al.  Current status of modern analytical luminescence methods , 2003 .

[12]  Larry J. Markoski,et al.  Microfluidic fuel cell based on laminar flow , 2004 .

[13]  O. Melnyk,et al.  Combined nanogap nanoparticles nanosensor for electrical detection of biomolecular interactions between polypeptides , 2004 .

[14]  Saif A. Khan,et al.  Microfluidic synthesis of colloidal silica. , 2004, Langmuir : the ACS journal of surfaces and colloids.

[15]  Shawn D. Llopis,et al.  Contact conductivity detection in poly(methyl methacrylate)-based microfluidic devices for analysis of mono- and polyanionic molecules. , 2002, Analytical chemistry.

[16]  R. Ismagilov,et al.  Combining microfluidic networks and peptide arrays for multi-enzyme assays. , 2005, Journal of the American Chemical Society.

[17]  M. Shikida,et al.  Fabrication of thermal-isolation structure for microheater elements applicable to fingerprint sensors , 2002 .

[18]  M. Shikida,et al.  Three-dimensional interconnect technology on a flexible polyimide film , 2004 .

[19]  P. Hauser,et al.  Conductimetric and potentiometric detection in conventional and microchip capillary electrophoresis , 2002, Electrophoresis.

[20]  S. Lunte,et al.  Fabrication and evaluation of a carbon‐based dual‐electrode detector for poly(dimethylsiloxane) electrophoresis chips , 2001, Electrophoresis.

[21]  Koji Inoue,et al.  Low-voltage and low-power optimization of micro-heater and its on-chip drive circuitry for gas sensor array , 2002 .

[22]  D. Bornhop,et al.  Detection in capillary electrophoresis , 2000, Electrophoresis.

[23]  Dino Di Carlo,et al.  Nanogap capacitors : Sensitivity to sample permittivity changes , 2006 .

[24]  S. Quake,et al.  Dynamic pattern formation in a vesicle-generating microfluidic device. , 2001, Physical review letters.

[25]  Y. Zohar,et al.  Micromachined polycrystalline thin film temperature sensors , 1999 .

[26]  Minoru Taya,et al.  Design of Micro-Temperature Sensor Array With Thin Film Thermocouples , 2005 .

[27]  R A Mathies,et al.  Capillary electrophoresis chips with integrated electrochemical detection. , 1998, Analytical chemistry.

[28]  Liang Li,et al.  Using a multijunction microfluidic device to inject substrate into an array of preformed plugs without cross-contamination: comparing theory and experiments. , 2007, Analytical chemistry.

[29]  M. Schwarz,et al.  Recent developments in detection methods for microfabricated analytical devices. , 2001, Lab on a chip.

[30]  Method to sense single-particle motion using a tapered-gap microcapacitor , 2004 .

[31]  Abraham P Lee,et al.  Microfluidic flow transducer based on the measurement of electrical admittance. , 2004, Lab on a chip.

[32]  Srinivas Tadigadapa,et al.  Thin film temperature sensor for real-time measurement of electrolyte temperature in a polymer electrolyte fuel cell , 2006 .

[33]  J. V. Hatfield,et al.  Polyimide membrane for micro-heated gas sensor array , 2004 .

[34]  Manz,et al.  Integrated potentiometric detector for use in chip-based flow cells , 2000, Analytical chemistry.

[35]  P. Bergveld,et al.  Theoretical and experimental determination of cell constants of planar-interdigitated electrolyte conductivity sensors , 1995 .

[36]  G. Kaltsas,et al.  Porous Silicon Membranes over Cavity for Efficient Local Thermal Isolation in Si Thermal Sensors , 2004 .

[37]  Bruce K. Gale,et al.  Electrical conductivity particle detector for use in biological and chemical micro-analysis systems , 1998, Photonics West - Micro and Nano Fabricated Electromechanical and Optical Components.

[38]  R. Besser,et al.  A micromachined thin-film gas flow sensor for microchemical reactors , 2006 .

[39]  A Manz,et al.  Chemical amplification: continuous-flow PCR on a chip. , 1998, Science.

[40]  Duk-Dong Lee,et al.  A micro hot-wire sensors for gas sensing applications , 2004 .

[41]  Xingyu Jiang,et al.  Potentiometric titrations in a poly(dimethylsiloxane)-based microfluidic device. , 2004, Analytical chemistry.

[42]  C. Gau,et al.  Heat exchanger fabrication with arrays of sensors and heaters with its micro-scale impingement cooling process analysis and measurements , 2004 .

[43]  Albert van den Berg,et al.  New approaches for fabrication of microfluidic capillary electrophoresis devices with on‐chip conductivity detection , 2001, Electrophoresis.

[44]  Takashi Kobayashi,et al.  The Prandtl micro flow sensor (PMFS) : a novel silicon diaphragm capacitive sensor for flow-velocity measurement , 1998 .

[45]  M. Dijkstra,et al.  Micromachined two dimensional resistor arrays for determination of gas parameters , 2003, TRANSDUCERS '03. 12th International Conference on Solid-State Sensors, Actuators and Microsystems. Digest of Technical Papers (Cat. No.03TH8664).

[46]  Gijsbertus J.M. Krijnen,et al.  Micromachined structures for thermal measurements of fluid and flow parameters , 2001 .

[47]  Susan M Lunte,et al.  Development of a microfabricated palladium decoupler/electrochemical detector for microchip capillary electrophoresis using a hybrid glass/poly(dimethylsiloxane) device. , 2004, Analytical chemistry.

[48]  S. Lunte,et al.  Microchip capillary electrophoresis/ electrochemistry , 2001, Electrophoresis.

[49]  Frédéric Ginot,et al.  Electrical detection of DNA hybridization based on enzymatic accumulation confined in nanodroplets. , 2005, Analytical chemistry.

[50]  M. Shikida,et al.  Thermal characterization of micro heater arrays on a polyimide film substrate for fingerprint sensing applications , 2005 .

[51]  J J Heijnen,et al.  Integrated electrochemical sensor array for on-line monitoring of yeast fermentations. , 2006, Analytical chemistry.

[52]  E. Verpoorte.  Chip vision-optics for microchips. , 2003, Lab on a chip.

[53]  Sigurd Wagner,et al.  Capacitive sensing of droplets for microfluidic devices based on thermocapillary actuation. , 2004, Lab on a chip.

[54]  Helen Song,et al.  Formation of droplets and mixing in multiphase microfluidics at low values of the Reynolds and the capillary numbers , 2003 .

[55]  Hilmi,et al.  Electrochemical detectors prepared by electroless deposition for microfabricated electrophoresis chips , 2000, Analytical chemistry.

[56]  K. Mogensen,et al.  Recent developments in detection for microfluidic systems , 2004, Electrophoresis.