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1766664 
Journal Article 
Development of ultra-miniature pressure sensors for 1-French biomedical applications and beyond 
Gowrishetty, U; Walsh, K; Aebersold, J; Rousse, T; Millar, H; Jackson, D 
2008 
1 
Sensor Letters
ISSN: 1546-198X 
6 
3 
433-440 
WOS:000257793100012 
A 0.69-French piezoresistive pressure transducer for ultra-miniature biomedical applications is designed and batch-fabricated using SOI (silicon on insulator) and DRIE (deep reactive ion etching) technologies. One of the major applications of this device is for blood pressure monitoring using 1-French catheters. The combination of SOI and DRIE technologies results in uniform diaphragm thickness and complete elimination of the post-processing dicing step by micromachining "die separation streets" during the DRIE process. The dimensions of the ultra-miniature die are 650 mu m x 230 mu m x 150 mu m (length, width, thickness) with a 2.5 mu m thin silicon diaphragm fabricated using (100) n-type 100 mm SOI wafer. The piezoresistive gauges were formed using ion implantation and their bond pads are directly solderable using an aluminum/titanium/platinum metallization strategy. The sensors configured in a half Wheatstone bridge produced a sensitivity of 27-31 mu V/V/mmHg with a non-linearity of +/- 0.77%, TCO of 110 mu V/degrees C and a drift of 1 mmHg/day. The batch fabrication process resulted in approximately 20,000 dice per wafer. Finite element analysis was used to determine the optimum gauge location and compared to analytical predictions and experimental results. 
piezoresistive pressure sensor; 1-french catheter-tip sensors; biomedical applications; silicon on insulator and deep reactive ion etching technology