Biochemical microsystems with integrated photodiode arrays of improved sensitivity and functionality

Otto Leistiko; Peter Friis

doi:10.1117/12.350055

3 June 1999 Biochemical microsystems with integrated photodiode arrays of improved sensitivity and functionality

Otto Leistiko, Peter Friis

Proceedings Volume 3606, Micro- and Nanofabricated Structures and Devices for Biomedical Environmental Applications II; (1999) https://doi.org/10.1117/12.350055
Event: BiOS '99 International Biomedical Optics Symposium, 1999, San Jose, CA, United States

Abstract

In order to determine the maximum efficiency obtainable for the Mesa photodiodes used in our integrated bio/chemical microsystems, devices of different geometry have been integrated with optical waveguides and a simple microfluidic system in a test chip. Also, in order to study the effect of increasing the interaction length between the chemicals in the microchannel and the measuring light beam, a second integrated system was designed and fabricated. Two different geometries were studied, one in which the light is transmitted through the liquid in a direction perpendicular to the axis of a microchannel 50 micrometer wide and another in which the light is transmitted along the axis of a microchannel 5 mm long. The latter geometry was used in order to increase the interaction length between the light and the liquid by a factor of 100, thus, increasing the detection sensitivity by approximately 20 dB. The systems were fabricated employing two substrates which were bonded together, a silicon wafer containing the optical circuitry, plus one half of the microchannel circuitry, and a Pyrex wafer containing the other half of the microchannel circuitry. The planar multimode waveguides which formed the optical circuits were low loss ((alpha) less than or equal to 0.5 dB/cm) germanosilicate glass structures while the photodetectors were special, 'end-fire,' coupled Mesa structures having a good sensitivity (maximum R approximately equals 0.5 A/W) and broad spectral response ((lambda) approximately equals 350 - 1000 nm). In order to make more realistic studies of the detection sensitivity, simple chemical analyses such as phosphate determinations were performed using the chips made.

Citation Download Citation

Otto Leistiko and Peter Friis "Biochemical microsystems with integrated photodiode arrays of improved sensitivity and functionality", Proc. SPIE 3606, Micro- and Nanofabricated Structures and Devices for Biomedical Environmental Applications II, (3 June 1999); https://doi.org/10.1117/12.350055

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