Tactile sensor

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A tactile sensor is a device that measures touch and other physical interactions with its surroundings. It works like skin, sensing mechanical touch, temperature, and sometimes pain (pain sensing is rare in machines). Tactile sensors are used in robotics, electronics, and security, and you’ll find them in touchscreens on phones and computers.

There are several types of tactile sensors, including piezoresistive, piezoelectric, optical, capacitive, and elastoresistive sensors. Some use camera-like technology to capture high-resolution touch data, such as Gelsight, or transparent gels to combine touch and visuals, like the STS sensor. A common idea is a pressure sensor array made of many small sensing points called tactels. Each tactel detects normal (pushing) force, and together they create a tactile image of the contact surface.

Materials used for these sensors include conductive rubber, lead zirconate titanate (PZT), PVDF and PVDF-TrFE, FET-based elements, and metallic capacitive sensors. Pressure sensor arrays can be very thin and are used both for research and in robotics, as well as in industry for testing manufacturing processes.

Tactile sensing is not just about feeling; it helps test and improve many products, from car parts like brakes and seals to batteries and joints. In medicine, tactile imaging turns the sense of touch into a digital image, similar to a clinician palpating tissue with a finger.

Robots use touch to go beyond what vision can tell them. Seeing an object doesn’t reveal its weight, texture, stiffness, center of mass, friction, or how it conducts heat. Tactile sensors provide this extra information when a robot grips something, aiding safe handling and manipulation. Different robot systems use various tactile methods, including pressure sensors, force distribution sensors, and multi-direction force detection.

Biologically inspired designs range from whisker-like sensors that detect a single point to fingertip or full-skin sensors. Modern designs often combine several sensing strategies to measure pressure distribution, the pattern of forces, and sometimes vibrations and heat. These multiple signals help robots understand texture, shape, and how objects slide against each other.

New sensors even fuse force sensing with vibration and heat transfer sensing. A notable bio-inspired sensor has achieved very precise touch, enabling robots to navigate without sight (0.2 mm precision) and recognize textures with about 97% accuracy, while remaining robust in real-world use.

Open-hardware and affordable options are making tactile sensing more accessible. Cheaper optical cameras and 3D-printed parts are enabling hobbyists and developers to experiment with tactile sensing without expensive equipment.