In order to convert the change in resistance of the sensor
into an electrical signal (voltage), a Wheatstone bridge circuit
(Figure 3A) is commonly used for signal processing in
piezoresistive sensing systems. There are two ways in
conventional MEMS to integrate signal processing circuits
with the MEMS sensor: (i) A two-chip approach, where a
MEMS device is mounted on a printed circuit board (PCB)
on which the signal processing circuit is laid out; the
electrical connection is achieved using wire-bonding [9]. (ii)
A monolithic approach, where a MEMS device and a
conventional IC signal processing circuit (e.g., CMOS) are
microfabricated on the same silicon chip (e.g.,
CMOS-MEMS) [10]. The monolithic approach provides
smaller chip footprint and much lower noise levels, but is
more complicated to fabricate