Capacitive keypads or FSR (force-sensing resistors) consist of a conductive elastomer, which changes resistance in a predictable manner following application of force to its surface.

The silicone consists of both electrically conducting and non-conducting particles suspended in matrix. The particles are sub-micrometre sizes, and are formulated to reduce the temperature dependence, improve mechanical properties and increase surface durability. Applying a force to the surface of a the sensing film causes particles to touch the conducting electrodes, changing the resistance of elastomere.

Like a resistive based sensor, capacitive keypads require a relatively simple interface and can operate satisfactorily in moderately hostile environments. Compared to other force sensors, the advantages of Abatek Capacitive Keypads are their size, low cost and good shock resistance.

Tactile sensing

Touch and tactile sensor are devices which measures the parameters of a contact between the sensor and an object. This interaction obtained is confined to a small defined region. This contrasts with a force and torque sensor that measures the total forces being applied to an object. In the consideration of tactile and touch sensing, the following definitions are commonly used:

Touch Sensing

This is the detection and measurement of a contact force at a defined point. Touch sensing can also be restricted to binary information, namely touch, and no touch.

Tactile Sensing

This is the detection and measurement of the spatial distribution of forces perpendicular to a predetermined sensory area, and the subsequent interpretation of the spatial information. A tactile-sensing array can be considered to be a coordinated group of keys.

Slip/Slide

This is the measurement and detection of the movement of an object. This can be achieved either by a specially designed slip/slide surface or by the interpretation of the data from a touch sensor or a tactile array.