title: A light detection cell to be used in a micro analysis system for ammonia.
abstract: This paper describes the design, realization and characterization of a micromachined light detection cell. This light detection cell is designed to meet the specifications needed for a micro total analysis system in which ammonia is converted to indophenol blue. The concentration of indophenol blue is measured in a light detection cell. The light detection cell was created using KOH/IPA etching of silicon. The KOH/IPA etchant was a 31 wt.% potassium hydroxide (KOH) solution with 250 ml isopropyl alcohol (IPA) per 1000 ml H(2)O added to it. The temperature of the solution was 50 degrees C. Etching with KOH/IPA results in 45 degrees sidewalls ({110} planes) which can be used for the in- and outcoupling of the light. The internal volume of the realized light detection cell is smaller than 1 mul, enabling measurements on samples in the order of only 1 mul. Measurements were performed on indophenol blue samples in the range of 0.02 to 50 muM. In this range the measurements showed good reproducibility.
authors.affiliation: MESA+ Research Institute, University of Twente (EL-TT), P.O. Box 217, 7500 AE, Enschede, The Netherlands.
authors.forename: R M
authors.initials: RM
authors.lastname: Tiggelaar
authors.forename: T T
authors.initials: TT
authors.lastname: Veenstra
authors.forename: R G P
authors.initials: RG
authors.lastname: Sanders
authors.forename: J G E
authors.initials: JG
authors.lastname: Gardeniers
authors.forename: M C
authors.initials: MC
authors.lastname: Elwenspoek
authors.forename: A
authors.initials: A
authors.lastname: van den Berg