Flexible Optical Tactile Force Sensor to Conduct Measurements From the Back of the Hand

The accurate and nonintrusive measurement of tactile information from the hand is crucial for various applications, such as in healthcare, robotics, augmented reality (AR)/virtual reality (VR), and sports. However, current technologies often hinder tactile sensation or restrict measurements to specific areas of the hands. This study presents a novel flexible optical tactile force sensor that can be attached to the back of the hand, thereby enabling the comprehensive measurement of tactile information without compromising natural tactile perception. This sensor enables the simultaneous estimation of pressure, force direction, and pulse wave information, thereby merging biomechanical and physiological monitoring. We demonstrated the sensor’s capability to estimate both the pressure and direction of the applied force by affixing the flexible optical sensor to the back of the hand, comparable with conventional palm-side sensors while preserving tactile sensation. This sensor simultaneously measures skin deformation and changes in blood volume, enabling the real-time acquisition of force and pulse wave data. Our innovative approach enables accurate and nonintrusive measurement of the tactile force on the hand and fingers while providing valuable physiological insights through pulse wave analysis. These advancements hold significant promise for healthcare applications, where the real-time monitoring of mechanical and cardiovascular data could significantly enhance diagnostic capabilities.