Peizoresistive pressure transducers part1

# Peizoresistive pressure transducers part1 - SEN2MET Chapter...

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SEN2MET Chapter 6, part 1 SEN2MET Chapter 6, part 1 Lecture plan week 41 1

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SEN2MET Chapter 6, part 1 Pressure sensors using piezoresistive readout - Pressure sensor designs based on different diaphragms - Design issues: Offset voltage, offset temperature variation, sensitivity variation with temperature, non-linearity - Calibration 2
SEN2MET Chapter 6, part 1 Piezoresistive pressure sensors Square and rectangular diaphragms designs Piezoresistive sensing with edge-mounted deflection bridges: Four 2-terminal resistors (shown here) – Single 4-terminal resistor Example with a square diaphragm with a deflection bridge at one of the diaphragm edges 3

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SEN2MET Chapter 6, part 1 Some repetitions Thevenin equivalent of deflection bridge with 4 piezoresisitors 00 (1 ) ) ) ) ) ) 11 22 th S th S th S R Ge R Ge EV R Ge R Ge R Ge R Ge Ge Ge E V Ge  +− =  + ++  = = Please note: Linearity between strain e and unloaded terminal voltage E th 12 14 23 () th S th RR R R Z R R = = + 4
SEN2MET Chapter 6, part 1 A detailed analysis of the diaphragm Stress in square diaphragms, Chap. 2.6.4 2 22 2 2 2 2 2 2 At the surface of the diaphragm (Eq. 2.177) with normalized variables: 0.51 (1 )(1 3 ) ) ) ) 2.045(1 ) )(1 XX YY XY a T p yx xy h a T p h a T p h ν  = +−  = = −−  2 ) xy 2 2 2 2 Maximum stress at center of edges ( ,0): 1.02 , 0 At center of diaphragm (0,0): 0.51(1 ) , 0 XX YY XX XY XX YY XY a a T p T TT h a T T pT h ± = = = = −+ = 5 42 2 2 2 For determination of the diaphragm strain and stress, we start with the displacement function (Eq. 2.176): 1 ( , ) ) (1 ) , max. at center of plate 47 For the normal stresses: ( 1 XX ax y wxy p Da a Ez T = = − 2 2 2 2 2 ), ( ) 1 For the shearing stress: 1 YY XY ww E

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## This note was uploaded on 05/30/2011 for the course SEN 2MET taught by Professor Ulrikhanke during the Spring '11 term at VCU.

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Peizoresistive pressure transducers part1 - SEN2MET Chapter...

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