Piezoresistive pressure sensors are one of the very-first products of MEMS technology. Those products are widely used in biomedical applications, automotive industry and household appliances. The sensing material in a piezoresistive pressure sensor is a diaphragm formed on a silicon substrate, which bends with applied pressure. A deformation occurs in the crystal lattice of the diaphragm because of that bending. This deformation causes a change in the band structure of the piezoresistors that are placed on the diaphragm, leading to a change in the resistivity of the material. This change can be an increase or a decrease according to the orientation of the resistors.

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6. Diffusion (n-type and p-type)
Metallization
Anisotropic back-side etching (by using
well known chemicals as TMAH or KOH)
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14. Household Appliances: Washing
machines, dishwashers, vacuum cleaners;
Automotive Applications: Oil level, gas
level, air pressure detection;
Biomedical Applications: Blood pressure
measurement, etc...
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15. Low-cost
sensor
fabrication
opportunity.
Mature
processing
technology.
Different
pressure
levels can
be
achieved
according
to the
application.
Also,
various
sensitivities
can be
obtained.
Read-out
circuitry
can be
either on-
chip or
discrete.
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you