Circuit Design (IMAGE) Tokyo Institute of Technology Caption Each sensor node consists of a circuit made of just a photovoltaic source, a variable resistor, a capacitor, two inductors and a bipolar transistor (top). One inductor is realized as a printed layer onto the circuit board and used for coupling (bottom, left). The overall design is quite compact, with the majority of the 32 × 32 mm board area taken up by the solar cells. Credit Minati L Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.