Energy efficiency and reliability of sensors are in many fields of application of essential importance. In particular medical sensors shows that for a intended in vivo use are extremely challenging. In addition to the desired low energy consumption are also many problems to solve, from the physiological conditions arise. The energy consumption of sensors is on the one hand determined by the integration technology used and on the other hand by the circuit concepts employed to gather the desired quantity. For a given integration technology an increase in energy efficiency is therefore achieved entirely by improvments of the circuit concepts. Best results are gained only by optimizing the complete conversion chain consisting of transducer design, the signal conditioning unit and information processing modules. The aim of the project is to establish a extensive expertise on energy-efficient, integrated circuit design for common readout procedures for medical sensor systems, in particular capacitive and resistive techniques by which the impedance of a transducer is to be converted into an electrical signal. Special Attention is paid to the requirements of implantable sensors with extremely low power consumption and DC-free power supply and output signals as well as compact devices. The practical implementation and verification is performed by implementations in the form of application specific integrated circuits (ASICs) for micromechanical inertial sensors and pressure sensors. At the end of the project there will be library of "best practice" circuit concepts established, that is verified with a few selected examples. ** This work is partially co-funded by the European Commission under the European Regional Development Fund according to article 4 ERDF and the county of Lower Austria.