What are the different types of smart pressure sensors? Are they all interchangeable?

At present, intelligent pressure sensors are divided into two categories:
piezoresistive and capacitive. According to the process and technology,
piezoresistive pressure sensors are divided into: metal strain type; glass
micro-melting type; diffusion silicon; ceramic pressure-resistive type; and
sputtering film type.

The ceramic capacitor type is slightly different in the shape of the
electrode and the treatment of the electrode surface according to the process
requirements and range. According to the application, it can be roughly divided
into three categories:

1. Large diaphragm with a diameter of 32mm. ( Applied to the monitoring of
industrial sites)

2. 21mm diameter small membrane. ( Applied to engine oil pressure
detection)

3. 16X16mm square membrane. ( Applied to automobile air conditioning pressure
detection)

The first is the piezoresistive pressure sensor.

1: Metal strain type

Metal strain technology is the oldest sensor technology. It is also the
earliest in various pressure sensor applications. The technology is mature and
widely adopted by small and medium-sized enterprises. It is mainly used for the
measurement of medium and high pressure (20Bar-1000Bar) and ultra-high pressure
(1000Bar or more).

Metal strain gauges are widely used in weighing sensors, and strain gauges
have the advantage of small temperature drift. At the same time, the small
sensitivity (generally 2mV/V) and the bridge resistance are small, which makes
it difficult to apply pressure transmitters, especially two-wire transmitters
with 4-20mA output, in circuit design, and the requirements for the circuit are
relatively high. With the development of digital circuit technology, this
problem has been basically properly solved. Major digital pressure transmission
IC manufacturers have provided better solution circuits. In addition, it should
be mentioned that many domestic enterprises do not have in-depth research on the
corresponding variable plate patch technology, and there are shortcomings in the
process, resulting in zero drift of the strain sensor, poor long-term stability
and insufficient overload resistance. However, at present, there is basically no
difference between domestic and imported metal strain sensors, and they have
been well solved in terms of technology and function.

2: Glass micro-melting type

Glass micro-melting technology was successfully developed by MSI in the
United States in the early 1990s and began mass production. In the mid-to-late
1990s, it was applied to the automobile industry by the American company TI. It
is mainly used for automotive EBD systems. In recent years, it has been applied
to engines with in-cylinder direct injection technology. Measuring pressure
range 7Bar-700Bar. With good mass production, the production technology of
silicon strain gauges is now mastered by foreign companies. At present, some
companies in China have been researched and developed and mass-produced, and the
reliability of the products has yet to be confirmed. There are also a few
companies that have started to produce micro-fusion pressure sensors.

The temperature characteristics of semiconductor silicon wafers are
relatively poor, usually greater than 10% FS/100 degrees, and temperature
compensation must be carried out. There are usually two ways of compensation:
analog compensation and digital compensation.

3: Diffuse silicon type

Diffusion silicon technology is a sensor technology that gradually developed
with the increasing maturity of semiconductor microelectromechanical technology
and other materials and auxiliary production technologies in the late last
century. It also has good mass production, but the manufacturing cost is
relatively high, the equipment investment is relatively large, and the process
flow is relatively long. Measuring pressure range 10Kpa -700Bar. The main
domestic manufacturers are Baoji Mike, Hengtong, Nanjing Gaohua, etc. At
present, it is rarely used in the automobile industry and mostly in the
industrial field. However, in recent years, Precision Electronics of the United
States has developed a low-cost diffusion silicon oil-filled pressure
transmitter for applications and automobiles.

4: Ceramic pressure resistance type

Ceramic piezoresistive technology is also mature. At the end of the last
century, the rigidity of ceramic itself determines that it is very suitable as a
sensor diaphragm material. In addition, the ductility characteristics of the
slumeter resistance material are matched with it as an ideal sensor technology
choice. At present, many companies at home and abroad produce it. However, there
is still a big gap between domestic companies and foreign companies in terms of
ceramic material sintering, share resistance materials and other auxiliary
materials and processes. The pressure measurement range is 1Bar-700Bar, but it
is not suitable for measuring impact high pressure.

It is also mass-produced, and GM has been applied to the field of automotive
oil pressure measurement. Pressure measurement within 50 Bar is relatively
extensive. The cost is relatively low.

5: SPLASHED FILM TYPE

The sputtering film technology is a new technology that developed at the end
of the last century with the maturity of the technology. It can be understood as
the development of strain gauge technology with the help of new technologies.
The measuring pressure range is 5Bar-1000Bar.

6: Ceramic capacitor type

Ceramic capacitance technology is a kind of capacitive sensor produced by the
linear principle of the inverse of the capacitance value of the parallel plate
capacitor and the plate spacing. The calibration of the capacitance sensor is
carried out by combining the digital circuit with the different charge and
discharge time of the capacitor. At present, only a few foreign companies can
mass-produce this technology. It is widely used in the industrial field and the
automotive field.

The core of ceramic capacitor production technology is the electrode
thickness of 1 micron and the electrode spacing of 20 microns. The overload
capacity of ceramic capacitors is better than that of other sensors. But digital
circuits must be used for amplification.

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