A device includes a coil (11) coupled to a magnetic field having power energy by electromagnetic induction, a rectifier (12) for subjecting the power energy fetched by the coil to full-wave rectification, a smoothing circuit (13) for smoothing a rectified output from the rectifier and forming a fixed internal power source, an MOS transistor (14) having a source and a drain connected in parallel across the coil, and a constant-voltage control circuit (15) adapted to be actuated to control the gate voltage of the MOS transistor in response to the output of the smoothing circuit, thereby limiting voltage (power) applied to the rectifier. The device further includes a data reception unit (21) for detecting a modulated component of the power energy fetched by means of the coil and receiving an information signal represented by the modulated, component and a data transmission unit (24) for controlling the gate voltage of the MOS transistor in response to transmission information, changing the extent of electromagnetic-induction coupling to the magnetic field of the coil, and transmitting the transmission information.

A measurement system having an analyzer unit (2; 102) and at least one replaceable sensor (1; 101). Each sensor has a transponder (13) in which sensor-specific data is stored. The analyzer unit has an antenna (21) for wireless readout of the data stored in the transponder and for wireless transmission of the power required to operate the transponder. The transponder (13) and the antenna of the analyzer unit (2) are further configured to additionally transmit and receive the measurement signal of the sensor (1) wirelessly. The sensor may be accommodated in a connecting unit (32, 52, 62, 72, 112) configured to be secured to a corresponding mating component (41, 56, 66, 76, 116).

The present invention teaches a method, system and units for measuring changes in blood during a longer period of time in vivo with a patient by measuring diffusivity of solvent. A differential pressure sensor is arranged on a silicon wafer or beam comprising resistors being in communication with fluids in two chambers via semipermable membranes enabling measuring of two components in said blood by tracking changes over time.

An implantable chip biosensor for detecting an analyte in vivo in body fluids comprises an analyte-sensitive hydrogel slab chemically configured to vary its displacement volume according to changes in concentration of an analyte, such as glucose, in a patient's body fluid, the slab being disposed in a groove in a support block. The biosensor chip is `read` by an external scanner configured to quantifiably detect changes in the displacement volume of the hydrogel slab. The support block is made of rigid or semi-rigid support material to restrain expansion of the hydrogel in all but one dimension, and the groove has one or more openings covered with a semipermeable membrane to allow contact between the patient's body fluid and the hydrogel. The scanning means may be any type of imaging devices such as an ultrasound scanner, a magnetic resonance imager (MRI), or a computerized tomographic scanner (CT) capable of resolving changes in the slab's dimensions.

Provided is a bio-sensor system which utilizes radio frequency identification technology and which includes a remote transponder in wireless communication with an implantable passively-powered on-chip transponder. The bio-sensor system is specifically adapted to provide a substantially stable and precise sensor reference voltage to a sensor assembly that is included with the on-chip transponder. The remote transponder is also configured to remotely receive data representative of a physiological parameter of the patient as well as identification data and may enable readout of one or more of the physiological parameters that are measured, processed and transmitted by the on-chip transponder upon request by the remote transponder. The precision and stability of the sensor reference voltage is enhanced by the specific circuit architecture of the glucose sensor to allow for relatively accurate measurement of the physiological parameter such as measurement of glucose concentration by a glucose sensor without the use of a microprocessor.