Generation of dynamic chemical signals with microfluidic C-DACs.
The utilization of microfluidic "lab-on-a-chip" devices in fundamental medical research, drug discovery and clinical diagnostics has rapidly increased in the past decade. Lab-on-a-chip devices process small volumes of analytes and reagents through on-chip microfluidic signal processing circuits. This paper discusses the implementation of a basic microfluidic circuit block, the concentration digital-to-analog converter (or C-DAC) which produces discretized chemical concentrations in a constant stream of solvent. The chemical concentration is controlled by a time-varying digital word; hence C-DACs are suitable for on-chip generation of arbitrary chemical signals. A 4-bit continuous-flow C-DAC was fabricated in two-level PDMS technology and tested. Several chemical waveforms (sawtooth, cosine, and ramp) were generated at flow rates of 2 microL min(-1) and frequencies of 0.6-4 mHz. The frequency cut off of this C-DAC was approximately 500 mHz.
Chen
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Electrical Engineering and Computer Science Department, Case Western Reserve University, Cleveland, OH, USA. lichen@case.edu
Azizi
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F
Mastrangelo
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CH
D001671:Biochemistry / Q000379:methods; D002621:Chemistry / Q000379:methods; D019963:Clinical Chemistry Tests / Q000295:instrumentation*; D003201:Computers; D005453:Fluorescence; D008832:Microchemistry / Q000295:instrumentation / Q000379:methods; D046210:Microfluidic Analytical Techniques; D044085:Microfluidics; D015233:Models, Statistical; D008962:Models, Theoretical; D010477:Perfusion; D013997:Time Factors