Crystalline cages create unusual ‘touchless’ sensors

Crystalline cages that adsorb water have found an unexpected application in the field of sensors. These supramolecular structures serve as ‘touchless’ sensors, by simply detecting the humidity that naturally surrounds the skin. The sensor ‘exhibits an exceptional responsiveness to humidity changes’, explains lead author Niveen Khashab, who works at the King Abdullah University of Science and Technology in Saudi Arabia. ‘It’s a more promising avenue for touchless technology,’ she adds.

Touchless technology could transform how we interact with computers and other machines. Since the start of the Covid pandemic, interest in touchless sensors has rocketed – market projections predict sales will triple by 2026, to an estimated to an estimated $37.6 billion. Traditionally, touchless sensors use ‘physical’ stimuli such as infrared radiation, ultrasounds or capacitance. In this case, chemistry is key. ‘Humidity sensors detect the presence of a finger, it’s very creative,’ says Jonathan Nitschke, an expert in supramolecular cages at the University of Cambridge, UK. ‘I had never heard of this application before.’