Multifunctional electronic skin integrating dual-mode optical and pressure sensors for caregiving robots

Advancements in artificial intelligence have broadened the capabilities of robots, particularly in caregiving applications that are essential for aging societies facing a growing shortage of human caregivers. Humanoid caregiving robots require sophisticated sensing systems to perform delicate tasks such as monitoring vital signs and providing physical assistance without causing discomfort. In particular, functionalities such as close-range proximity sensing, tactile feedback, and physiological and electrophysiological signal monitoring are essential for ensuring safe and effective caregiving. However, electronic skin (e-skin) capable of simultaneously detecting proximity, tactile, and physiological signals remains largely unexplored. Here, we present a multifunctional robotic e-skin that vertically integrates an optical sensor array and a pressure sensor array. The optical sensor, comprising quantum dot light-emitting diodes (QLEDs) and perovskite photodetectors (PDs), enables dual-mode sensing for both proximity detection and photoplethysmography (PPG) measurement. A carbon nanotube (CNT)-based pressure sensor array provides tactile feedback, ensuring stable and precise physiological monitoring. Additionally, the array structure allows cross-validation of proximity and PPG data, improving measurement accuracy and reliability. This multifunctional e-skin represents a significant advance toward the development of caregiving robots capable of safe, precise, and sophisticated human-robot interaction.