title: Miniature liquid flow sensor and feedback control of electroosmotic and pneumatic flows for a micro gas analysis system.
abstract: Accurate liquid flow control is important in most chemical analyses. In this work, the measurement of liquid flow in microliters per minute was performed, and feedback control of the flow rate was examined. The flow sensor was arranged on a channel made in a polydimethylsiloxane (PDMS) block. The center of the channel was cooled by a miniature Peltier device, and the change in temperature balance along the channel formed by the flow was measured by two temperature sensors. Using this flow sensor, feedback flow control was examined with two pumping methods. One was the electroosmotic flow method, made by applying a high voltage (HV) between the reagent and waste reservoirs; the other was the piezo valve method, in which a micro-valve-seat was fabricated in a PDMS cavity with a silicone diaphragm. The latter was adopted for a micro gas analysis system (microGAS) for measuring atmospheric H2S and SO2. The obtained baselines were stable, and better limits of detection were obtained.
authors.affiliation: Department of Science, Kumamoto University, 2-39-1, Kurokami, Kumamoto 860-8555, Japan.
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Ohira
authors.forename: Kei
authors.initials: K
authors.lastname: Toda
mesh_terms: D000393:Air Pollutants / Q000032:analysis; D004129:Dimethylpolysiloxanes / Q000737:chemistry; D004563:Electrochemistry / Q000379:methods; D019075:Electrophoresis, Capillary / Q000295:instrumentation / Q000379:methods; D005246:Feedback; D006862:Hydrogen Sulfide / Q000032:analysis*; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods*; D044085:Microfluidics / Q000295:instrumentation* / Q000379:methods*; D009995:Osmosis; D012680:Sensitivity and Specificity; D012828:Silicones / Q000737:chemistry; D013458:Sulfur Dioxide / Q000032:analysis*; D013696:Temperature
chemical_list: D000393:Air Pollutants; D004129:Dimethylpolysiloxanes; D012828:Silicones; D013458:Sulfur Dioxide; C013830:baysilon; D006862:Hydrogen Sulfide