Wilhelm, Stefan and Wolfbeis, Otto S. (2010) Opto-chemical micro-capillary clocks. MICROCHIMICA ACTA, 171 (3-4). pp. 211-216. ISSN 0026-3672, 1436-5073
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Opto-chemical capillary clocks are presented that are based on the measurement of a colored segment in a microchannel (a capillary). Color is created by a chromogenic chemistry involving the oxidation of a (virtually colorless) leuco-dye. Poly(ethylene glycol) (PEG) is used as a solvent, and indigo and thioindigo (in their reduced leuco forms) act as oxygen-sensitive dyes. The clock is started by removing one seal at the end of the capillary. A visible color change occurs as air diffuses into the microchannel due to an irreversible color reaction. The length of the colored segment is proportional to the time elapsed. PEGs of different average molar mass affect the diffusion rate of oxygen in the microchannel and thereby affect the rate of the migration of the color front. Both temperature and relative humidity exert a strong effect. Six types of such clocks are described that enable times to be determined in the range from 1 day to 6 months, possibly of even decades.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | TIME-TEMPERATURE INTEGRATOR; POLYETHYLENE-GLYCOL; FRESHNESS; INDIGO; REDUCTION; PHOSPHATE; Optical timer; Chromogenic chemistry; Indigo; Oxygen; Clock; Poly(ethylene glycol) |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Analytische Chemie, Chemo- und Biosensorik > Chemo- und Biosensorik (Prof. Antje J. Bäumner, formerly Prof. Wolfbeis) |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 06 Jul 2020 09:38 |
| Last Modified: | 06 Jul 2020 09:38 |
| URI: | https://pred.uni-regensburg.de/id/eprint/23811 |
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