A ferrofluid-based wireless pressure sensor

Girish Chitnis, Purdue University, Birck Nanotechnology Center
Babak Ziaie, Purdue University, Birck Nanotechnology Center

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This paper presents a wireless pressure sensor design based on magnetic fluid displacement over a planar coil and its corresponding inductance change. The design of the pressure sensor is presented followed by its fabrication and characterization. Experimental results show a good correlation with a nonlinear model relating the applied pressure to the change in coil self-resonant frequency. A prototype sensor (radius = 6 mm, thickness = 2 mm) based on the above principal using an oil-based ferrofluid (50 mu l, ferrite concentration 2%), a polyimide-embedded planar coil (L = 1 mu H), and a 25 mu m thick polyimide membrane shows a sensitivity of 3 KHz mmHg(-1) with a base-line resonant frequency of f(0) = 109 MHz.


Nanoscience and Nanotechnology