Smart devices play vital role due to their responsiveness to stimuli like heat, temperature, pH, stress in our lives. These devices have changed our lives as compared to our ancestors. Wearable devices need energy to function which can be provided by batteries but recharging them timely is not feasible so energy to run these devices is harnessed from the mechanical energy of the body. Wearable device should have less Young’s modulus and elastic limit should be high. These devices can be integrated into items of daily use like bracelets, armbands, wristwatches, rings, vests, shoes and gloves. Wearable devices provide numerical or graphical data via sensors.