Our group is developing various energy harvesters based on solar cell, piezoelectric and triboelectric devices. Using these energy harvesters, we are developing self-powered sensors that don’t need batteries. The information of external input sources like pressure, vibration, and temperature could be obtained by analyzing the generated electric output signals. Many factors from environmental parameters change the output voltage and current from the energy harvesters. We strive to design and develop self-powered sensor systems that can be of service to our real life.