A diode-based two-wire solution for temperature-compensated piezoresistive pressure sensors

A novel two-wire solution for ultraminiaturized temperature-compensated piezoresistive pressure sensors is presented. The technique makes it possible to measure both pressure and temperature separately by using bias-controlled diodes as switches between the pressure and temperature sensing elements. The p-n junction diodes are forward-biased or reverse-biased depending on the polarization of the voltage supply. The new diode-based two-wire technique was evaluated using a surface micromachined pressure sensor where the pressure-sensing element consists of a piezoresistor on an (80/spl times/40/spl times/1 /spl mu/m) double end supported force- transducing beam. The beam is located beneath a (100/spl times/100/spl times/2 /spl mu/m) square polysilicon diaphragm having its ends attached to the diaphragm and to the cavity edge. The thermal compensation piezoresistor is also located in the cavity on a (100/spl times/40/spl times/1 /spl mu/m) beam. Both ends of this beam are attached to the cavity edge and are therefore pressure-insensitive. The new detection solution enables a reduction of conducting leads from three to two in combination with high pressure sensitivity (0.7 /spl mu/V/V/mmHg) and environmental isolation compared to a commercialized traditional piezoresistive pressure sensor. Its simplicity and the potential for size reduction due to fewer bonding pads and conducting wires make it ideal for applications such as disposable blood pressure sensors where cost and size are critical parameters.

[1]  Darko Belavic,et al.  Silicon pressure sensors with a thick film periphery , 1998 .

[2]  J. Bryzek,et al.  Disposable blood pressure sensors with digital on-chop laser trimming , 1988, IEEE Technical Digest on Solid-State Sensor and Actuator Workshop.

[3]  E. Obermeier,et al.  An interchangeable silicon pressure sensor with on-chip compensation circuitry☆ , 1989 .

[4]  M. A. Shanblatt,et al.  A fully integrated temperature compensation technique for piezoresistive pressure sensors , 1993 .

[5]  Martin Hill,et al.  Development and characterisation of a surface micromachined FET pressure sensor on a CMOS process , 1999 .

[6]  M.N. Horenstein.  A direct gate field-effect transistor for the measurement of DC electric fields , 1985, IEEE Transactions on Electron Devices.

[7]  Lennart Löfdahl,et al.  Small piezoresistive silicon microphones specially designed for the characterization of turbulent gas flows , 1994 .

[8]  A. Nakladal,et al.  Influences of humidity and moisture on the long-term stability of piezoresistive pressure sensors , 1995 .

[9]  Ernest Otto Doebelin,et al.  Measurement Systems Application and Design , 1966 .

[10]  Andreas Schroth,et al.  Ambient humidity and moisture - a decisive failure source in piezoresistive sensors , 1995 .

[11]  W. Ko,et al.  Development of a miniature pressure transducer for biomedical applications , 1979, IEEE Transactions on Electron Devices.

[12]  Y. Haga,et al.  MICROMACHINED 125μm DIAMETER ULTRA MINIATURE FIBER-OPTIC PRESSURE SENSOR FOR CATHETER , 2000 .

[13]  Peter Enoksson,et al.  A free-hanging strain-gauge for ultraminiaturized pressure sensors , 2002 .

[14]  Mark N. Horenstein.  Microelectronic circuits and devices (2nd ed.) , 1995 .

[15]  Per Ohlckers,et al.  Compensation of sensitivity shift in piezoresistive pressure sensors using linear voltage excitation , 1995 .

[16]  L. Tenerz,et al.  The first surface micromachined pressure sensor for cardiovascular pressure measurements , 1998, Proceedings MEMS 98. IEEE. Eleventh Annual International Workshop on Micro Electro Mechanical Systems. An Investigation of Micro Structures, Sensors, Actuators, Machines and Systems (Cat. No.98CH36176.

[17]  G. Kowalski.  Miniature pressure sensors and their temperature compensation , 1987 .

[18]  Göran Stemme,et al.  Media protected surface micromachined leverage beam pressure sensor , 2001 .

[19]  O. Gregory,et al.  A self-compensated ceramic strain gage for use at elevated temperatures , 2001 .

[20]  Khalil Najafi,et al.  An ultraminiature CMOS pressure sensor for a multiplexed cardiovascular catheter , 1992 .

[21]  K.D. Wise,et al.  Scaling limits in batch-fabricated silicon pressure sensors , 1987, IEEE Transactions on Electron Devices.

[22]  L. Tenerz,et al.  A fiberoptic silicon pressure microsensor for measurements in coronary arteries , 1991, TRANSDUCERS '91: 1991 International Conference on Solid-State Sensors and Actuators. Digest of Technical Papers.