Sensors and their uses, including: touch sensors incorporated within detection devices used to measure fluid levels (for example, cooling water level in nuclear power plants), temperature sensors, light sensors to measure light level, light sensors to detect light source, for example, in a car park barrier system, moisture sensors to measure water content of soil, pH sensors to measure the acidity of soil, gas sensors, infrared sensors to detect movement of human bodies which emit heat, for example, in burglar alarm systems, (electro)magnetic field sensors, ultrasonic sensors, the use of induction (inductive) loops in car parking and car park barrier systems, sound sensors in burglar alarm systems, proximity sensor in smartphones to switch off screen display when phone is held near to the ear