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A micromachined Kelvin probe for surface potential measurements in microfluidic channels and solid-state applications

Publication Type:

Conference Paper

Source:

TRANSDUCERS '03. 12th International Conference on Solid-State Sensors, Actuators and Microsystems. Digest of Technical Papers (Cat. No.03TH8664), IEEE, Volume vol.1, Boston, MA, USA, p.384-7 (2003)

URL:

http://dx.doi.org/10.1109/SENSOR.2003.1215334

Keywords:

contact potential; discharges (electric); electric actuators; microfluidics; pH; silicon compounds; surface potential

Abstract:

This paper reports on a micromachined Kelvin probe structure with integrated scanning tip and dither actuation mechanism. It is fabricated by a modified micro electro-discharge machining process which allows electrical isolation within the micromachined structure using epoxy plugs. The device is used to measure changes in the external surface potential of a parylene microfluidic channel as a function of varying pH of liquid inside the channel. A contact potential difference of \≈6 V is measured for a change in pH from 4 to 8 within the channel. The device is also used to map embedded charge in a thin SiO2 layer on a Si substrate, showing it to be suitable for monitoring microelectronics manufacturing processes