This paper presents a remotely powered sensing tag for biomedical applications. Energy is transfered by an EM-field to a dual frequency band antenna and fed to an analog front end. The AC voltage resulting on the antenna gets rectified, pumped to 3.3V and stored in an 2.2μF buffer capacitor. When the buffer capacitor is full a measurement with an integrated impedance measurement circuit can be processed while the RFID field is deactivated to get a noise reduced measurement sample. The circuit is developed in a 130nm CMOS technology and occupies an active area of 2.3mm².