Humidity measurement has become vital for most applications in industries today. Humidity sensing has a wide range of applications which include, but are not limited to, food storage & refrigeration, HVAC, industrial process control, test & measurement (t&m), automotive, and medical & healthcare.
Humidity Measurement Applications with Outstanding Stability
A careful balance of humidity is often necessary. Slight changes in the relative humidity content in applications, for example breathing air controllers (anesthesia), may make the patient nauseous or may even affect the anesthetic result.
Stable detection of an appropriate humidity level with an acceptable response time is one of the crucial tasks in humidity measurement. It is mandatory to cover the entire measurement range from 0% RH to 100% RH. Obviously, stability should remain unchanged, even if operated under elevated conditions over years.
Temperature and the environmental aspects of the individual application significantly impact the stability requirements in the long run. Humidity sensors often show their weaknesses when exposed to extreme humidity conditions, aggressive chemicals, or temperature cycling.
Figure 1. Layers of an IST AG capacitive humidity element
The P14-W is a standard humidity sensor that was specifically developed to meet the wide range of applications in HVAC, industrial fields, white goods and in test & measurement. It is optimal for various application needs, and is available with wires and as SMD.
There is a huge demand for ultra-fast, robust and stable humidity sensors within metrology applications, such as weather balloons and radio-sondes. The entire sensor operation has to be granted, not only at normal temperatures, but also under elevated environmental constraints such as high radiation levels, extremely low temperatures, and extreme condensation. Such applications require fully customized solutions, such as those offered by the P14 Rapid.
P14 2FW Thermo
Designed specifically for dew-point applications and humidity generators, the P14 2FW Thermo is a one-chip solution, consisting of a capacitive humidity sensor, based on the popular P14 sensor, along with a heating element that is also a valid Pt1000 or Pt100 sensor. Thanks to optimal thermal coupling, excellent measurement accuracy is achieved which makes users' application cutting-edge in the industry.
P14 FemtoCap (SMD)
The FemtoCap, despite its very small sensor size, has excellent sensor characteristics that are needed in white goods and automotive fields. It provides an excellent cost-to-performance ratio, when combined with external electronics. Currently, the Femtocap is one of the smallest capacitive humidity sensors available in the market, and is an optimal, cost-efficient sensor solution.
MK33 is a specially-developed capacitive humidity sensor featuring a base capacitance of 300 pF. It has a measuring range from 0% RH to 100% RH between -40 °C and +190 °C, and is optimal for oil measurement applications. The sensor comes with rigid or flexible connecting wires which make it the preferred choice for installation in detecting probes.
The K5 was developed for use in applications where accurate measurements in low humidity ranges were required. It has a small dimension and high sensitivities. The main characteristics of the sensor are its excellent stability in low humidity, high chemical resistance, and very low drift. With these superior characteristics, the K5 is the optimal choice for use in low-humidity environments.
Digital Humidity and Temperature Modules
The fully calibrated digital humidity modules, HYT are the latest additions to the IST AG humidity family, combining the benefits of a precise, capacitive humidity sensor element with the high integration functionality and density of an ASIC.
The module can completely process the measured data with the help of the integrated signal processing capability and directly delivers the physical parameters of relative humidity and temperature over the I2C-compatible interface.
Temperature drift and linearity error are corrected “OnChip” through computation which ensures excellent accuracy over a wide range of applications. The modules are completely interchangeable and the pins can be used with commercial standards.
Figure 2. Calibrated digital humidity and temperature modules – HYT 271, HYT 221 and HYT 939 (from the left).
IST AG ensures consistent high quality with the use of the P14 humidity sensor with a high-performance polymer. Characteristics of the sensors are excellent long-term stability and high chemical resistance in key application areas with high humidity and after dew formation.
Measurements up to 190 °C and 100 % RH with External Humidity and Temperature Sensor
Equipped with external sensors, the analog and digital modules (LinPicco™ and DigiPicco™ series) present another contribution to those customers who do not have an in-house electronic development and need a plug & play device, which can be easily connected to, for example, display equipment or valve controllers in a cost-effective way.
The LinPicco or DigiPicco combination with an external sensor results in highly accurate results while measuring very high humidity and temperatures. IST AG offers multiple variations in this regard.
- No distortion of signals and microclimate
- Wire lengths are offered up to 15 m, whereas 1 m is the standard
- The electronics are not exposed to high humidity and temperatures
Figure 3. Lin-/DigiPicco module with extended cable and external humidity and temperature sensor for use in high humidity and temperature applications.
This information has been sourced, reviewed and adapted from materials provided by Innovative Sensor Technology, USA Division.
For more information on this source, please visit Innovative Sensor Technology, USA Division.