title: Generation of dynamic chemical signals with pulse code modulators.
abstract: The on-chip generation of dynamic chemical signals in a flow stream via pulse code modulation (PCM) is demonstrated. In this chip the output signal concentration is determined by dispersion and averaging of a serial stream of digitally encoded plugs of concentrated solute and pure solvent as the plugs flow through a long dispersive capillary. A two-bit PCM chemical signal generator was fabricated in two-level PDMS technology. The chip was capable of generating 31 distinct output levels with 10-plug cycles. Several example chemical waveforms (sawtooth and cosine) were generated at flow rates of 43.2 nL s(-1), and plug frequencies of up to 15 Hz, with maximum output signal bandwidth of up to about 1 Hz. The modulator chip was also used to synthesize physiological signals emulating intracellular beta-cell cytosolic Ca(2+) oscillations, extracellular beta-cell insulin release and rat-striatum dopamine release.
authors.affiliation: Electrical Engineering and Computer Science Department, Case Western Reserve University, Cleveland, OH, USA.
authors.forename: F
authors.initials: F
authors.lastname: Azizi
authors.forename: C H
authors.initials: CH
authors.lastname: Mastrangelo
mesh_terms: D000818:Animals; D001479:Basal Ganglia / Q000378:metabolism; D002118:Calcium / Q000032:analysis* / Q000378:metabolism; D019963:Clinical Chemistry Tests / Q000295:instrumentation / Q000379:methods*; D003600:Cytosol / Q000737:chemistry / Q000378:metabolism; D004298:Dopamine / Q000032:analysis* / Q000378:metabolism; D005109:Extracellular Matrix / Q000737:chemistry / Q000378:metabolism; D050417:Insulin-Secreting Cells / Q000378:metabolism; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation / Q000379:methods*; D051381:Rats; D013997:Time Factors
chemical_list: D002118:Calcium; D004298:Dopamine