title: High resolution gas volume change sensor.
abstract: Changes of gas quantity in a system can be measured either by measuring pressure changes or by measuring volume changes. As sensitive pressure sensors are readily available, pressure change is the commonly used technique. In many physiologic systems, however, buildup of pressure influences the gas exchange mechanisms, thus changing the gas quantity change rate. If one wants to study the gas flow in or out of a biological gas pocket, measurements need to be done at constant pressure. In this article we present a highly sensitive sensor for quantitative measurements of gas volume change at constant pressure. The sensor is based on optical detection of the movement of a droplet of fluid enclosed in a capillary. The device is easy to use and delivers gas volume data at a rate of more than 15 measurements/s and a resolution better than 0.06 microl. At the onset of a gas quantity change the sensor shows a small pressure artifact of less than 15 Pa, and at constant change rates the pressure artifact is smaller than 10 Pa or 0.01% of ambient pressure.
authors.affiliation: Laboratory of Biomedical Physics, University of Antwerp, Groenenborgerlaan 171, Antwerp, Flanders B-2020, Belgium.
authors.forename: Joris J J
authors.initials: JJ
authors.lastname: Dirckx
authors.forename: Jef E F
authors.initials: JE
authors.lastname: Aernouts
authors.forename: Johan R M
authors.initials: JR
authors.lastname: Aerts
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D005740:Gases / Q000032:analysis* / Q000737:chemistry*; D044085:Microfluidics / Q000295:instrumentation* / Q000379:methods; D010783:Photometry / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014159:Transducers
chemical_list: D005740:Gases