Force sensing is used in a wide variety of applications and one of the primary methods of detection is the use of capacitance sensors. These sensor systems are based on parallel plate and MEMS technology. The force is detected by the shift in capacitance value. This response is nonlinear with respect to the load range and leads to a mismatch between the perception of the human operator and the actual output level. The systems are also difficult to scale due to higher cost of MEMS for larger sized sensors.
The technology developed enables accurate detection of volume changes even in low load range by employing micro-pillars (micro-protrusions) which are just tens of microns in dimension. These micron structures are formed in a conductive rubber using an original microfabrication technology. These capacitive sensors have a high linearity with respect to the load and provide a more intuitive operation where human perception matches the output characteristics. The sensitivity characteristics – linearity, load range, and capacitive response to load, can be tuned to suit the application by adjusting the design of the micropillars. Since the change in capacitance is governed by the deformation behaviour of the conductive rubber, this technology is also robust and has a high durability and lifespan.
This capacitive force sensors technology based on microfabrication technology has the following features –
The technology can be used to provide a much better user interface for various input devices spanning multiple technology fields –
Use case as a sensor exist in both industrial and commercial products –
The technology provides a highly durable force sensing solution which is well suited for long and continuous usage. The linear output characteristics and the possibility to tune the output by design make it ideal for use in several applications, especially where human operators are involved.