Bio-sensors - Medical Applications

The Sensors and microsystems session at ISSCC included
microwave radar chips for remote medical monitoring, and
a CMOS DNA-screening system.

Remote Medical Monitoring Chip
The single-chip, direct conversion 1.6GHz Doppler radars,
using 0.25pm CMOS and BiCMOS, were described by
researchers from Stanford University, Bell Labs and Agere
Systems.

The devices, claimed to be the first of their type to be
integrated in low-cost sfficon, use an active balun
amplifier to split a voltage controlled oscillator (VCO)
signal into an RF output and a local oscillator (LO) signal.

The reflected RF signal is mixed with the LO, and since
they are derived from the same source, the mixer
downconverts the RF signal to baseband. The output is
proportional to the movement of the target - in this case
displacement due to breathing and heartbeat. The
transceivers detected these vital signs 500mm from the
subject.

DNA Sensor Array Chip


A DNA sensor array chip based on 0.5pm CMOS, with
some extra steps to add gold electrodes, was presented
by German researchers from Infineon and Siemens, among
others.

The active sensor array is made from pairs of gold
electrodes in a circular compartment, onto which DNA
strands with known sequences (probes) are fixed. A
solution of unknown sequence (target) DNA strands is
washed across the chip, and compatible strands bind
to the fixed probes. Unreacted strands are washed
off.

After enzyme labels on the target DNA are chemically
converted to charge-carrying species, potentials are
applied to the interleaving electrode grids.

A pixel circuit on the 16x8the generator and collector
electrodes. The currents of both electrodes are amplified
using dual current irrors in series with each branch.
A dynamic range of five array reads current from both
decades of current is needed.


  


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