Sticky notes, aluminum foil, sponges, tape: it sounds like the recipe for a MacGyver escape device, but it’s not. In a field dominated by high-tech processes and painstakingly-engineered materials, a group of researchers have come up with a low cost design for flexible sensors that also have multiple functions.
Scientists at King Abdullah University of Science and Technology (KAUST) wanted a simple sensor that could detect multiple stimuli, including touch, pressure, temperature, acidity, and humidity. The paper responds to humidity, the sponges sense pressure, and the metal foil detects motion. Adding graphite from a pencil to the paper made it sensitive to acidity. The properties of the different materials respond to different inputs, resulting in a measurable change in the electrical properties of the combined device. Acidity affects the resistance of the electrical circuit, temperature changes the voltage, and bringing a finger near the device causes changes in its capacitance.
The result is a single, low-cost platform that can be used to measure multiple inputs simultaneously. It is lightweight and flexible, making it attractive for wearable applications, where its properties could be used to monitor a patient’s vital signs.