Piezoresistive Tactile Sensing

Measuring pressure from a material’s change in electrical resistance under load; cheap and easy to build into large sensor arrays.

The piezoresistive effect is a change in a material’s electrical resistivity when it is deformed by force; Lord Kelvin first observed it in metals in 1856, and in 1954 Smith found the effect to be far larger in silicon and germanium. Piezoresistive tactile sensors apply this effect to conductive rubber, conductive polymer film, or silicon strain elements: resistance changes under pressure, so measuring resistance gives pressure, and many such elements arranged in a row-and-column electrode grid can output a full pressure-distribution map. The technology is structurally simple, cheap, thin, and flexible, and can measure static force, making it one of the most common tactile approaches; the force-sensing resistor (FSR) belongs to this family. Its drawbacks are relatively high hysteresis and drift, and lower precision. 3D-ViTac (2024) sandwiches a Velostat piezoresistive film between conductive yarn electrodes to build a 16×16 tactile pad.

Example3D-ViTac attaches piezoresistive tactile pads to gripper fingers, at a cost of about US$20 per pad including the readout board, giving the policy a pressure value at every contact point.

Also called

Piezoresistive Sensor, Piezoresistive Tactile Array, Force-Sensing Resistor (FSR)

Related

Tactile Sensor · Tactile Array · Piezoelectric Tactile Sensing · Capacitive Tactile Sensing · Strain Gauge · 3D-ViTac

Sources

Piezoresistive effect - Wikipedia
Force-sensing resistor - Wikipedia
3D-ViTac: Learning Fine-Grained Manipulation with Visuo-Tactile Sensing (arXiv 2410.24091)