Characterization of an Integrable Single-Crystalline 3-D Tactile Sensor

Porous-Si-micromachining technique was used for the formation of single-crystalline force-sensor elements, capable of resolving the three vector components of the loading force. Similar structures presented so far are created from deposited polycrystalline Si resistors embedded in multilayered
$hboxSiO_2/hboxSi_3hboxN_4$
membranes, using surface micromachining technique for a cavity formation. In this paper, the authors implanted four piezoresistors in an n-type-perforated membrane, having their reference pairs on the substrate in order to form four half bridges for the transduction of the mechanical stress. They successfully combined the HF-based porous-Si process with conventional doping and Al metallization, thereby offering the possibility of integration with readout and amplifying electronics. The
$300 times 300 muhboxm^2$
membrane size allows for the formation of large tactile arrays using single-crystalline-sensing elements of superior mechanical properties. They used the finite-element method for modeling the stress distribution in the sensor, and verified the results with real measurements. Finally, they covered the sensors with different elastic silicon–rubber layers, and measured the sensor's altered properties. They used continuum mechanics to describe the behavior of the rubber layer.