Integrated electrical sensor arrays in microfluidic networks

Matthew C. Cole, Paul J A Kenis

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

As microfluidic networks continue to decrease in size and increase in complexity, the ability to monitor the passage of material throughout them becomes ever important. Many current microfluidic sensing techniques commonly employ optical methods based on differences in the refractive index of fluids. These techniques, though accurate, can often be complicated and difficult to incorporate with the rest of the microfluidic fabrication process. A promising alternative to these optical sensors involves the use of small electrical elements embedded in microfluidic devices. These electrical sensors can be simpler, less expensive, and can offer a greater number of sensors per unit area than their optical counterparts. We have used thin film resistive heaters to demonstrate the detection of discrete plugs of alternating fluids in a microchannel. A small voltage is applied to a resistor photolithographically patterned on the substrate of a microfluidic channel, and the corresponding current is measured. Changes in current signify changes in the thermal conductivity of the fluid surrounding the resistor, and therefore changes in the type of fluid. Using a low thermal conductivity polyimide as the channel substrate helps amplify heat transfer from the resistor to the fluid. This is a simple method to determine whether or not a certain fluid is present at a certain location in a microfluidic network. A similar system can be envisioned using conductive sensing. In such a system, two electrodes separated by a small gap are patterned on the bottom of a microfluidic channel. A constant current is applied to the circuit, and the voltage drop across the gap is monitored. Fluctuations in the potential correspond to changes in the conductivity of the fluid passing over the electrodes. We will report on our efforts to fabricate, implement, and characterize resistive and conductive sensor elements in large-scale microfluidic networks.

Original languageEnglish (US)
Title of host publication05AIChE
Subtitle of host publication2005 AIChE Annual Meeting and Fall Showcase, Conference Proceedings
Pages11968
Number of pages1
StatePublished - 2005
Externally publishedYes
Event05AIChE: 2005 AIChE Annual Meeting and Fall Showcase - Cincinnati, OH, United States
Duration: Oct 30 2005Nov 4 2005

Other

Other05AIChE: 2005 AIChE Annual Meeting and Fall Showcase
CountryUnited States
CityCincinnati, OH
Period10/30/0511/4/05

ASJC Scopus subject areas

  • Engineering(all)

Fingerprint Dive into the research topics of 'Integrated electrical sensor arrays in microfluidic networks'. Together they form a unique fingerprint.

  • Cite this

    Cole, M. C., & Kenis, P. J. A. (2005). Integrated electrical sensor arrays in microfluidic networks. In 05AIChE: 2005 AIChE Annual Meeting and Fall Showcase, Conference Proceedings (pp. 11968)