The Development Trend Of Humidity Sensor

In the industrial and agricultural production, weather,silicon, ceramic humidity resistance and so on.
environmental protection, national defense, scientificHumidity resistance has the advantage of high
research, aerospace and other departments aresensitivity, the main drawback is that linearity and
often required to measure and control humidity.interchangeability of products poor.b Humidity
However, in conventional environmental parameters,Capacitance
the humidity is the most difficult to accuratelyHumidity capacitors are generally made with the
measure a parameter. With the dry and wet bulbpolymer film capacitors, polymer materials commonly
hygrometer or a hair hygrometer to measureused in polystyrene, polyimide, cellulose acetate, etc.
humidity, the method has long been unable to meetbutyricum. When the ambient humidity changes, the
the needs of the development of modern sciencecapacitance of the dielectric constant humidity
and technology. This is because the measurement ofchanges, so that it is also a change in capacitance, its
humidity than the measurement of complexcapacitance is proportional to the change in relative
multi-temperature, the temperature is measured is anhumidity. The main advantage of capacitive humidity
independent, while the humidity is affected by othersensor with high sensitivity and product
factors (atmospheric pressure, temperature) effects.interchangeability is good, fast response, a small
In addition, the calibration of humidity is also aamount of moisture lag, easy to manufacture, easy
problem. Production abroad humidity calibrationto achieve miniaturization and integration, and its
equipment prices are very expensive.accuracy in general is lower than the humidity
In recent years, the humidity sensor research andsensitive resistor. The main production abroad
development at home and abroad have made greathumidity capacitor manufacturers are Humirel
strides. Humidity sensor is moving from simplecompany, Philips Company, Siemens Corporation. To
humidity sensor to the integrated, intelligent,Humirel produced SH1100-type humidity sensor
multi-parameter detection of the direction of rapidcapacitor, for example, the measurement range is
development, in order to develop a new generation(1% ~ 99%) RH, at 55% RH when the electrical
of humidity / temperature measurement and controlcapacity of 180pF (typical value). When the relative
system has created favorable conditions for humidityhumidity from 0 to 100%, the changes in capacitance
measurement techniques will also be raised to a newrange is 163pF ~ 202pF. The temperature coefficient
level.of 0.04pF / ℃, humidity hysteresis amount of ±
The characteristics of humidity sensor1.5%, response time of 5s.
Humidity sensor is the simplest humidity sensor.In addition to resistive, capacitive humidity sensor,
Humidity sensor are mainly resistive, capacitive twothere are ionic-type humidity sensor, weight-type
broad categories.a humidity sensitive resistorhumidity sensor (with a sense of the changes in the
Humidity resistance is characterized by the substrateweight of wet film to change the oscillation
covered by a layer of wet material with a sense offrequency), light intensity-type humidity sensor, SAW
the film, when the air in the water vapor adsorbedhumidity sensor and so on.
on a sense of the wet membrane, the componentsHumidity sensor linearity and anti-pollution poor in the
of the resistivity and resistance values are changeddetection of ambient humidity, the humidity sensor to
to use this feature Humidity can be measured. Manya long-term exposure to the environment under test,
different types of humidity resistance, such as metalit is easily affected by pollution, measurement
oxide humidity resistance, humidity resistance ofaccuracy and long-term stability.