Laser Direct Writing of Copper Circuits on Flexible Substrates for Electronic Devices

There are increasing interests in flexible electronic devices for sports, entertainment, health monitoring and medical cares. In particular, flexible sensors (wearable strain senor or robotic controllable sensors) attached on clothing or human skins could be used as a motion detector. Copper has been considered as a potential alternative material for other expensive noble metals. By laser-induced direct reduction and transfer printing, microsensors based on conducting copper circuits was fabricated on polydimethylsiloxane or polyimide as cheap and sensitive devices. A specific electrical resistivity of 240 mu Omega center dot cm of Cu circuit was successfully achieved in an electrode of about 40 mu m in thickness. We demonstrate a motion sensing based on laser-reduced copper circuits with a high sensitivity and mechanical robustness.