If you keep up with our blog here at Nelson-Miller, you’re probably familiar with the general concept of capacitive touchscreen technology. Touchscreen devices powered by capacitive technology identify touch commands by measuring capacitance. When a change of capacitance occurs, the device is able to pinpoint the exact location where the user touched, thereby responding with the appropriate action (e.g. opening an app, launching a program, entering a letter or number, controlling a web browser, etc.). To perform this operation, though, a touchscreen device must feature a variety of components, including capacitive sensors.
To better understand capacitive sensors, you must first look at the principle of capacitive sensing. Also known as capacitance sensing, capacitive sensing is the technology powering capacitive touchscreen devices. They differ from resistive touchscreen devices by identifying touch commands based on change of capacitance rather than pressure. Capacitive touchscreen devices project a small and uniform electrical charge across the display. When a user touches this display, his or her finger absorbs some of the electricity. It’s not enough for the user to notice, but the device is able to identify this change of capacitance so that it can determine the location of the user’s touch.
Capacitive touchscreen devices use sensors to facilitate capacitive sensing. The sensors are responsible for identifying the location of the user’s touch. If you touch the display of a capacitive device, some of the device’s electrical charge will transfer from the display — specifically the sensor where the touch occurred — to your body. The sensor tells the device that the touch occurred on a specific area, and the device is able to respond by performing the appropriate action.
Capacitive Sensor Material
Because capacitive touchscreen devices rely on change of capacitance to identify touch commands, capacitive sensors must be designed using a capacitive material. There are several different materials used to create capacitive sensors, one of which is copper. Copper is strong, durable and highly conductive, making it ideal for use in capacitive devices. Indium tin oxide (ITO) is another popular choice for capacitive devices. Like copper, it’s also strong and conductive, meaning it supports capacitive sensing. Finally, printed ink is a viable alternative for capacitive sensors. Assuming the ink is conductive, it too can work with conductive touchscreen devices.
Capacitive sensors are just one component in capacitive touchscreen devices. They also contain batteries, memory, computer processes and more.