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Integrated Piezoresistive Normal Force Sensors Fabricated Using Transfer Processes with Stiction Effect Temporary
Ni Liu1, Peng Zhong2,3, Chaoyue Zheng2,3
1Department of Nephrology, Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200032, China.
Micromachines
|May 28, 2022
Summary
This study details a novel fabrication method for integrated piezoresistive normal force sensors using surface micromachining. The developed tactile sensors can detect both normal and shear forces, advancing robotics and medical diagnostics.
Area of Science:
- Materials Science
- Mechanical Engineering
- Electrical Engineering
Background:
- Tactile sensation is critical for advanced robotics and pulse diagnosis instruments.
- Existing tactile sensors often lack the integrated functionality and sensitivity required for sophisticated applications.
- Surface micromachining offers a pathway for fabricating miniaturized, high-performance sensors.
Purpose of the Study:
- To present the fabrication of an integrated piezoresistive normal force sensor using surface micromachining.
- To demonstrate a novel transfer process for integrating the sensor with a readout circuit chip, overcoming stiction challenges.
- To explore the potential for developing multi-modal tactile sensors capable of detecting both normal and shear forces.
Main Methods:
- Fabrication of a piezoresistive normal force sensor via surface micromachining.
- Implementation of a temporary stiction effect handling process for sensor transfer.
- Integration of the sensor onto a readout circuit chip with operational amplifiers forming an instrumentation amplifier.
- Utilizing a flip-chip bonding technique with precise alignment for sensor transfer.
Main Results:
- Successfully fabricated an integrated piezoresistive normal force sensor with dimensions of 180 μm × 180 μm × 1.2 μm.
- Achieved a maximum misalignment of 1.5 μm during flip-chip bonding.
- Demonstrated a sensor sensitivity of 93.5 μV/μN/V.
- Showcased the adaptability of the piezoresistive Wheatstone bridge routing for shear force sensing.
Conclusions:
- The presented surface micromachining and transfer technique enables the creation of highly integrated tactile sensors.
- The developed sensor exhibits excellent sensitivity and precision, suitable for robotic and medical applications.
- The fabrication methodology can be extended to create tactile sensors capable of detecting both normal and shear forces, paving the way for advanced haptic feedback systems.
