| Recently, effort has been put forth to develop autonomous sensors. Such devices are designed to be capable of scavenging power in a remote environment or to operate from an on-board power supply. Sensors are typically designed with communications capabilities in order to transmit data from the sensor to a base station. However, communications capabilities limits the size of autonomous sensors and increases power requirements. In this thesis, a sensor architecture is developed based on electrochemical operation in order to reduce power requirements and the overall device size. In addition, the sensor effectively stores the data on-board, eliminating the need for communications capabilities.; An extremely small metal-ion sensor based on mass sensing and electrodeposition is developed with a compact photovoltaic cell power supply. Electrochemical systems are advantageous because of their ability to operate at very low powers with low voltage and current requirements. These systems can be the basis for sensor devices using an electrodeposition process in addition to chemical or drug delivery systems based on the electrochemical dissolution of thin metal membranes. A metal-ion sensor architecture is used to demonstrate the electrochemical device system. The development of a metal-ion sensor is detailed including theoretical aspects of operation including electrochemical theory, cantilever mechanics and mass loading effects, and photovoltaic cell operation.; The integrated metal-ion sensor uses a resonant cantilever mass sensor to detect electrodeposited metal at an electrode at the tip of the cantilever. The resonant cantilever is 150 mum in length. 40 mu m in width, and 0.6 mum in thickness and capable of measuring approximately 0.2 ng of deposited metal. The electrodeposition mechanism is driven by an integrated photovoltaic cell array consisting of three series connected photocells. The photovoltaic power supply is capable of producing an output power of 4.02 muW under illumination intensities of 80 W/m2 and the electrodeposition system operates at power levels of 50.2 nW and is integrated with the power supply into a total volume of approximately 0.046 mm3. |
