A Force Sensor is defined as a transducer that converts an input mechanical force such as load, weight, tension, compression, or pressure into an electrical output signal. As the force applied to the force sensor increases, the electrical signal changes proportionally. Force Sensors are also generally known as Force Transducer and it is also termed as a load cell or weight sensor.
How a Force Sensor Works
- The working principle of a force sensor is that most force sensors are created with the use of force-sensing resistors. Such sensors consist of electrodes along with sensing film. The force sensor responds to the applied force which converts the value to a measurable quantity.
- Force-sensing resistors are based on contact resistance. These contain a conductive polymer film, which predictably changes its resistance once force is applied on the surface.
- This conductive polymer film includes non-conducting, micrometer-sized, and electrically conducting particles, which are arranged in a matrix. If force is applied to the film’s surface, micro-sized particles touch the sensor electrodes, which change the film’s resistance. The quantity of change may vary the resistance value that provides a measure of the applied force. Different efforts are made using several approaches like reducing the drift of polymer electrode configurations being tested with the sensor to boost the performance of force-sensing resistors.
- Force can be measured using various technologies. Depending on the application i.e thin-film sensors, strain gauges, or hydraulic force transducers are used.
Force measurement with thin-film sensors
- In these force measurements with thin-film sensors, the force acting has measured the force acting on it through strain-sensitive thin-film resistors. The atomic welding of the thin-film sensor to the deformation body has a particularly high long-term stability. For particularly high safety requirements, redundant force transducers with two measuring bridges can also be realized with one thin-film sensor. The force is measured by the changed electrical resistance of the thin-film sensor. The resistance changes as soon as the deformation body deforms. The electrical resistance is then converted by the sensor into a standardized output signal and can thus be processed and recorded.
Force measurement with strain gauges
- The strain gauge works on the principle of the thin-film sensor. Strain gauges can be precisely attached to the smallest surfaces. Force transducers with strain gauges are particularly flexible since they can be manufactured from a variety of materials and in a wide variety of shapes.
Force measurement with hydraulic force transducers
- The measuring body of a hydraulic force transducer contains a liquid that can immediately transmit the force acting to an analog or digital display. Special features of hydraulic force transducers are their longevity, robustness, and independent operation without any power supply.
Applications
- Force sensors are widely used in Commercial, Medical as well as Aerospace.
- Force measurement plays an essential role in road traffic. It is also used in trucks. This means that the axle load may be determined precisely to enable effective and fast monitoring.
- Force sensors are also used in several applications in the railway industry. They determine freight weights and passenger cars or the drawbar’s tractive forces.
