Rapid prototyping of resistive MEMS sensing devices on paper substrates

We have developed an inexpensive inkjet printing process to rapidly fabricate resistive sensor devices on paper substrates. We utilize the percolation based resistive change in inkjet-printed resistors based on carbon black (CB). We fabricated an ink with 2 wt% CB, 0.3 wt% binder and added 0.3 % sodium cholate as well as 0.5 wt% triton as surfactant to print strain sensitive resistors. To connect the resistors we inkjet-printed conductors with a resistivity of 1 Ω/sq. Cutting and folding the paper substrate yields a sensor with a 3-dimensional structure for use as a tactile input device as well as an inertial sensor with a sensitivity of 8 mV / V g. Since we use a commercial inexpensive inkjet printer and the design can be modified and tested within minutes, the process is especially useful to easily develop and test MEMS sensor models. Additional applications encompass disposable medical sensors, sensors for paper packaging, as well as very low cost strain sensing.