Integrate touch sensor into existing USB key

U2F Zero is a small USB key for FIDO U2F authentication. Currently it contains a mechanical button. This button should be replaced by a touch sensor/button. Also the PCB should be modified to fit into a given plastic casing which shape should remain unmodified. It needs to be considered that the user's finger will have a distance of ca. 3mm to the PCB. Potentially a spring or other solution may be required to make the sensor work. The firmware should be updated to support the touch sensor as well. Tasks: 1) Add USB plug and modify PCB dimension to fit the given casing. 2) Evaluate and suggest a touch sensor component under consideration of the available space, distance-to-finger, and component price. Your experience with touch sensors is important. 3) Modify PCB and replace physical button with touch sensor. Potentially other components need to be shifted to the backside of the PCB. 4) Update the firmware to support the touch sensor. The conventions and quality of the current firmware should be met. Required skills: - KiCad - The current PCB is designed in KiCad and should be modified using KiCad. - Touch sensors - You should design a solution which is small in size, cheap, and which works with the given casing. The major constrain is to make the sensor work with the given plastic casing which has a distance from finger to PCB of ca. 3mm. - C programming - The firmware which needs to be modified is written in C. - Work with git (Github) and commit single modifications separately. U2F Zero: [login to view URL]