Researchers at the Massachusetts Institute of Technology have designed a device that responds to mechanical stress by changing the color of a spot on its surface, according to a press release. Researchers note this could lead to 3-D printed, flexible, sensor-laden material. The research is published in Advanced Materials Technologies.
“In nature, networks of sensors and interconnects are called sensorimotor pathways,” Subramanian Sundaram, PhD, a graduate student at the Massachusetts Institute of Technology and lead researcher of the study, said in the release. “We were trying to see whether we could replicate sensorimotor pathways inside a 3-D printed object. So, we considered the simplest organism we could find.”
To demonstrate the feasibility of material, researchers constructed a T-shaped device with a wide base and elongated crossbar. The crossbar is made from an elastic plastic, with a strip of silver running its length. Researchers connected electrodes to the ends of the crossbar. The base of the T, made from rigid plastic, includes two printed transistors and a circle of semiconducting polymer, referred to as a pixel, that changes color when the crossbars stretch and modify the electrical resistance of the silver strip.
According to the release, researchers added a copper-and-ceramic heater to deposit the semiconducting plastic. The plastic is suspended in a fluid that is sprayed onto the device surface, and the heater evaporates the fluid, leaving a 200-nanometer layer of plastic.
Transistors in device separate the gate and the semiconductor with a layer of water that contains potassium salt. Charging the gate drives potassium ions into the semiconductor and changes its conductivity, according to the release. The layer of saltwater lowers the operational voltage of the device, so it can be powered with a 1.5-volt battery.
Sundaram S, et al. Adv Mater Tech. 2017;doi:10.1002/admt.201600257.
Disclosures: The researchers report no relevant financial disclosures.