A prototype sensor array was developed for use with laboratory automation to permit closed-loop control of liquid-levels in a multiwell microplate geometry. A simple electrical model for non-contact capacitance-based fluid sensors was extended to describe a fluid-level dependency. The new model shows that a charge-transfer based capacitance transducer employing a liquid-specific calibration can be used to obtain an output signal that varies linearly with the liquid-level when fringe-field effects are negligible. The calibration also compensates for liquid-to-liquid conductivity and permittivity differences. / The sensor was tested using sodium chloride (NaCl) and ethanol solutions to simulate the range of conductivity and permittivity typical in biological and chemical research. Measured capacitance was a second-order function of liquid volume due to fringe-field effects and was compensated for by adding a hardware-based calibration. Liquid-volume measurement error averaged 0.2% of the 120mul fill volume with a standard deviation of 0.6% (< mul). The maximum absolute error for all liquids was 2.7% (3mul).
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.100243 |
| Date | January 2006 |
| Creators | Seliskar, Daniel Peter. |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Biomedical Engineering) |
| Rights | © Daniel Peter Seliskar, 2006 |
| Relation | alephsysno: 002652801, proquestno: AAIMR38503, Theses scanned by UMI/ProQuest. |
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