Insole-type sensor that enables continuous sole touch sensing without external power supply

Smart insoles, particularly insole-type sensors, have attracted tremendous attention because they are promising candidates for analyzing motion in healthy individuals and patients. In this study, an insole-type sensor containing sensing parts of knits made of a conductive yarn was developed. The sensor continuously outputs AC currents/voltages without an external power supply while the sole of a person's foot contacts the sensing parts with and without a sock. The continuous output originates from currents/voltages in the body induced by ambient electromagnetic fields. Combining the insole-type sensor, wireless sound transmitters and receivers, and software application or program made it possible to detect continuously and wirelessly where the wearer's sole was touching or pressing and provide automatic notification when a person exits a room. The developed sensor can be used for, for example, assessing gait disturbance at an early stage or providing notification when a person with dementia exits a room.