Search

A flexible tactile sensor was proposed to measure the three-dimensional forces. The sensor consisted of a bump structure, top and bottom electrodes, a piezoelectric sensitive layer and a substrate layer. The top and the bottom electrodes were prepared by lift-off process. When a three-dimensional force was applied, the bottom four electrodes under the bump structure would collect different charge signals, which can be detected by the different electric current variations. In the experiments, when the forces range from 0 to 10N with different angles were applied to the bump structure, the sensor can measure forces with a best non-linearity of 1.89%. This proposed tactile sensor could be used in the intelligent robotics to measure multi-dimensional force.

An improved peninsula-island structured pressure sensor was presented with the novel dry-wet combination etching process. There were four pairs of segmented mass blocks attaching on the back of the diaphragm. Each segmented mass block was composed of a peninsula structure and an island structure with anisotropic-etching-induced sidewalls. The improved structure not only inherited the stress concentration feature of low strain energy dissipation but also improved the comprehensive ability of the sensor chip, including low fabrication cost, high etching uniformity, good temperature performance and low residual stress in the diaphragm. Also, the fabrication method combining DRIE (Deep Reactive Ion Etching) and anisotropic wet etching was verified by the simulation based on the Sentaurus 2013. The fabrication error caused by anisotropic wet etching was analyzed. Compared with the flat film of the same size, the proposed structure can increase the sensitivity by 225%, reduce the nonlinearity by 80.3%, and increase resonance frequency by 11%. In addition, the sensor structure can also be applied to pressure sensors with different working range, which will be helpful to design the pressure sensors with high efficiency and accuracy.

Lumped element model (LEM) for resonant chemical sensors based on the capacitive micromachined ultrasonic transducers (CMUTs) was developed and analyzed with electrical characterization. The CMUTs chip were functionalized with the electrospinning technology. Two Butterworth Van-Dyke (BvD) models for functionalized CMUTs were proposed and analyzed with different DC voltages. Considering the electrical phase with parasitic capacitance, the modified BvD model can be used to illustrate more comprehensive features for both mechanical impedance and phase properties. The parallel capacitance was measured accurately using an impedance analyzer, and the quality factor was calculated based on the proposed model under different DC voltages. These models will provide important theoretical basis for CMUTs-based chemical sensors to further electrical analysis and oscillator design.