Nowadays, humidity measurement is important for various applications in the industry. Humidity sensing is applied in automotive, medical and healthcare, HVAC, t&m, food storage and refrigeration, and industrial process control. These are just a few instances where humidity sensing plays a crucial role in people’s lives.
Humidity Measurement Applications with Outstanding Stability
Usually, humidity needs to be carefully balanced. Even slight variations in relative humidity content in applications such as breathing air controllers (anesthesia) could lead to nausea in patients or even affect the anesthetic result.
A stable detection of a proper humidity level with an acceptable response time is the most vital task in humidity measurement. It is mandatory to cover the entire measurement range from 0% RH to 100% RH. Obviously, it is essential that stability remains the same, even if operated under elevated conditions over years.
Temperature and environmental aspects of the individual application have considerable influence on the long term stability requirements. Often, the drawbacks of humidity sensors become apparent when they are subjected to aggressive chemicals, temperature cycling, or high or low humidity.
Figure 1. Layers of an IST AG capacitive humidity element.
The standard P14-W humidity sensor was developed to meet the wide range of applications in HVAC, white goods, test and measurement and in industrial fields, and is optimal for a wide variety of application needs - available with wires and as SMD.
Meteorology applications, such as weather balloons and radio sondes demand robust, stable, and ultrafast humidity sensors. The entire sensor operation has to be granted, both under normal conditions and under elevated environmental constraints such as under extreme condensation, high radiation levels, and extremely low temperatures. Fully tailored solutions demanded by these applications are provided by the P14 Rapid.
P14 2FW Thermo
The P14 2FW Thermo was particularly intended for applications in dew point applications and humidity generators. The favorable one chip solution consists of a capacitive humidity sensor, based on the popular P14 sensor, along with a heating element, which is also a valid Pt100 or Pt1000 sensor, simultaneously. The exceptional measurement accuracy achieved due to optimal thermal coupling makes users’ applications cutting edge in the industry.
P14 FemtoCap (SMD)
The FemtoCap has a very small size yet it has excellent sensor characteristics that are needed in areas such as white goods and automotive. Combined with external electronics, the FemtoCap provides an excellent cost to performance ratio. It is an optimal and cost-efficient sensor solution, and at present, P14 FemtoCap is one of the most compact capacitive humidity sensors available on the market.
IST has specially developed a capacitive humidity sensor that features a base capacitance of 300 pF. It is optimal for oil measurement applications with a measuring range from 0% RH to 100% RH from -40 °C to +190 °C. The sensor comes with flexible or rigid connecting wires, making it the most preferred choice for installation in detecting probes.
With its high sensitivity and small dimension, the K5 was developed for applications which require accurate measurements in low humidity ranges. Outstanding stability in low humidity, a high chemical resistance, and very low drift are characteristics of the sensor. Thanks to its excellent sensor characteristics, the K5 is the ideal choice in low humidity environments.
Calibrated Digital Humidity and Temperature Modules
Figure 2. Calibrated digital humidity and temperature modules - HYT 271, HYT 221 and HYT 939. (from the left)
The latest members of the IST AG humidity family are the fully calibrated digital humidity modules, HYT, which integrate the benefits of a precise, capacitive humidity sensor element with the high integration density and functionality of an ASIC.
Using the integrated signal processing, the module completely processes the measured data and directly provides the physical parameters of temperature and relative humidity over the I2C compatible interface. Both the temperature drift and linearity error are corrected “OnChip” through computation, thus assuring exceptional accuracy over a broad range of applications. The modules are completely interchangeable and the pins are compatible with commercial standards.
IST AG’s consistent high quality is assured by the use of the P14 humidity sensor with a high performance polymer. The sensors are characterized by a high chemical resistance and an excellent stability in critical application areas over extended periods of time with high humidity and after dew formation.
Measurements up to 190 °C and 100% RH with External Humidity and Temperature Sensor
The analog and digital modules (LinPicco™ and DigiPicco™ series) with external sensors present another feature for customers who do not have their own 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 very cost-effective manner.
The combination of a LinPicco or DigiPicco module with an external sensor results in exceptional accuracy while measuring very high temperatures and humidity. In this regard, IST AG provides multiple variations.
Figure 3. Lin-/DigiPicco module with extended cable and external humidity and temperature sensor for use in high humidity and temperature applications.
- Wire lengths are offered up to 15 m, whereas 1 m is standard
- Distortion of signals and microclimate are non-existent
- The electronics are not exposed to high temperatures and humidity
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.