Out-of-plane high-density piezoresistive silicon microwire/p-n diode array for force- and temperature-sensitive artificial whisker sensors

摘要

We propose an out-of-plane high-aspect-ratio 'whisker-like' microwire array sensor for use in multisite contact force and temperature detection with high spatial resolution. Although the wire element has two terminal electrodes, the device consists of force-sensitive wire arrays where one end of the wire is attached to the substrate and the other end is free to be touched. We fabricated a force-sensitive wire array based on p-type (p-) silicon with 3μm diameter and 30 μm length (1 Ω cm) assembled over an n-type (n-) silicon substrate (3-6 Ω cm), which resulted in a p-silicon wire/p-n diode system array. Due to the piezoresistance effect of the p-silicon wire, the electrical conductance changes upon contact of an individual wire with an object. The shift in the rectifying current-voltage (I-V) curves of the embedded p-n diode depends on the temperature through the silicon wire. Thus, the same alignment can be used as a force sensor and a temperature sensor. Both force- and temperature-sensitive microwire sensor arrays with a small detection area (～20 μm~2) and high spatial resolution (～100μm in pitch) have potential in numerous applications, including artificial electronic fingertips in a robot hand/prosthetics, multisite sensing of contact force, shear force, surface roughness and slip, and local temperature sensing capabilities.