Simulation, fabrication and characterization of a 3D piezoresistive force sensor

• Published in: Sensors and actuators. A. Physical. Vol. 147; no. 2; pp. 430 - 435
• Main Authors: Tibrewala, A., Phataralaoha, A., Büttgenbach, S.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 03-10-2008
• Subjects: Diffused silicon piezoresistors; Force sensor; Force sensor; Diffused silicon piezoresistors
• ISSN: 0924-4247; 1873-3069
• DOI: 10.1016/j.sna.2008.05.020

In this contribution we report on a miniaturized bulk micro-machined three-axes piezoresistive force sensor. The force sensor consists of a full membrane with 16 conventional two terminal p-type diffused piezoresistors on the surface of the membrane. The die size of the chip is 6.5
mm
×
6.5
mm. Piezoresistors with four different designs were placed on the membrane. Sensitivities were found to be in the range of 0.37–0.79
mV/(V
mN) and 1.68–2.92
mV/(V
mN) in
Z-direction and
X- or
Y-direction, respectively. The stiffness of the measured microprobes in the range of 5–8
mN/μm and 0.27–0.48
mN/μm were obtained in vertical and lateral direction, respectively. Various single and twin membranes designs were simulated to calculate stiffness of the microprobe. The measurement results show a cross-axis sensitivity of <2.5% at full scale of 25
mN.