Although the materials of the flexible PCB aren’t expandable, we have succeeded in realizing a stretchable PCB by combining laser cutters and papercutting (kirie) techniques.
(Developed Product) Picture: Working sample of an EMG with Ag/AgCl electrodes fixed as supporters without any need for gel.
Biomedical electrodes that can stretch according to the various forms of the body are needed to measure ECG, EEG and EMG. At Elephantech, we have succeeded in achieving a stretchable circuit board type biomedical electrode by using a laser cutter to add papercutting incisions to a flexible PCB. As with standard flexible PCB, this stretchable PCB has a constant resistance value through its expansion range and allows for soldering.
Biological electrodes to measure myoelectric potential
How the non-stretchable flexible PCB can stretch
The particularity of the materials used in flexible PCB is that, while not expandable, it can be bent. Comparing it to an origami pattern, the red area buckles from the plane and becomes a curved surface in order to allow the entire sheet to stretch in appearance. As with standard flexible PCB, this stretchable PCB maintains a constant resistance value through its expansion range and allows for soldering. In addition to this, by elongating this red area, even sheets made of thick or hard materials can be easily bent or stretched. As an example, it can also be applied to making flexible PCB with thick and durable materials.