New pressure sensor boasts enhanced sensitivity

Citation

(2003), "New pressure sensor boasts enhanced sensitivity", Sensor Review, Vol. 23 No. 3. https://doi.org/10.1108/sr.2003.08723caf.002

New pressure sensor boasts enhanced sensitivity

New pressure sensor boasts enhanced sensitivity

Keywords: Pressure sensors, Silicone

Everyone knows that a good caregiver should be sensitive to the needs of others, but what about robot caregivers? A newly developed pressure sensor is pliant like the skin and sensitive enough to detect even the lightest touch correctly. This would give the robot just the sensitivity that it needs to find usage in the health-care field that is believed to find a brisk market in this new century. Other potential applications are seen as high-performance sensors for automotive and computer uses.

The new pressure sensor brings together the sensor technologies of the Inaba Rubber Company, Ltd, located in Osaka prefecture in the central Kinki region of central Japan, with the well-developed know-how of the Osaka University Institute of Scientific and Industrial Research. The device is an example of a nanocomposite, a composite made by mixing different materials at the microscopic level so as to create a new material with unique properties. In another case, tiny beads of carbon ranging from 1 to 10 microns (one millionth of a metre) in diameter and particles of an alumina-type ceramic of around 20 nm (one billionth of a metre) in diameter are mixed into silicone rubber that is melted in a crucible.

Silicone-rubber is not conductive and the nanocomposite at rest will not allow the electric current to pass. The carbon particles do conduct electricity, however, so that when pressure is applied and the composite deforms and carbon particles come into contact with one another, they form a pathway for the flow of electricity. This is the mechanism used by the pressure sensor to signal that it has touched or has been touched by something.

The alumina particles help to disperse the carbon particles more evenly throughout the silicon rubber, making the flow of current more evenly distributed and more stable. At the same time, limiting the alumina helps preserve the flexibility and the rubber's elasticity. This is not the first time that a pressure sensor has been developed by mixing conductive particles into rubber, but rubber tends to harden over time and change its characteristics, making it hard to produce reliable sensors.

Another problem is that the stiff rubber needs to be loosened up before it can be used, so it is not practical to incorporate the sensors on industrial production lines. The new pressure sensor can detect contacts across a continuous range of forces from a very light touch to a strong pressure. When the pressure is relaxed, the device returns to its original shape and, in addition, the sensor can be processed into both flat and rounded shapes.

The new pressure sensor locates the ends of objects with five optoelectronic sensors that are lined up longitudinally and laterally, and that memorialise and process all information quickly such as that stored in a tiny LSI chip. The compact device, says the Osaka University Institute, "could become the feeling hand of a future robot." The Institute thus visualises the development "as the robot hand of any automated machine selected."