%0 Conference Paper %B TRANSDUCERS '03. 12th International Conference on Solid-State Sensors, Actuators and Microsystems. Digest of Technical Papers (Cat. No.03TH8664) %D 2003 %T A micromachined Kelvin probe for surface potential measurements in microfluidic channels and solid-state applications %A Chu, L L %A Takahata, K %A Selvaganapathy, P %A Shohet, J L %A Gianchandani, Y B %C Boston, MA, USA %I IEEE %K contact potential,discharges (electric),electric actuators,microfluidics,pH,silicon compounds,surface potential %P 384-7 %U http://dx.doi.org/10.1109/SENSOR.2003.1215334 %V vol.1 %X 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 %9 inproceedings