In electrical engineering, capacitive sensing is a technology,
based on capacitive coupling, that takes human body capacitance
as input. Capacitive sensors detect anything that is conductive
or has a dielectric different from that of air. Many types of
sensors use capacitive sensing, including sensors to detect and
measure proximity, position or displacement, humidity, fluid
level, and acceleration. Human interface devices based on
capacitive sensing, such as trackpads, can replace the computer
mouse. Digital audio players, mobile phones, and tablet
computers use capacitive sensing touchscreens as input devices.
Capacitive sensors can also replace mechanical buttons.
Capacitive sensors are constructed from many different media,
such as copper, Indium tin oxide (ITO) and printed ink. Copper
capacitive sensors can be implemented on standard FR4 PCBs as
well as on flexible material. ITO allows the capacitive sensor
to be up to 90% transparent (for one layer solutions, such as
touch phone screens). Size and spaci