Technological leadership:

These innovations are based on monolithic thermopile sensors. Now, sensors with a maximum resolution of 160x120px and a minimum pixel size of 45µm in a TO-8 package are possible, using modern semiconductor technologies and microelectromechanical system (MEMS) methods. The latest developments, e.g. in the design/geometry of the pixel or the absorber material hand in hand with the appropriate selection of the protective gas or wafer level packaging (WLP) and a suitable optical coating the latest sensor generations lead to a significant increase in the signal-to-noise ratio SNR.  This not only has a positive effect on thermal resolution (NETD), but also enables more competitive pricing through optimizations in optics.

In direct comparison to competing methods (e.g. microbolometer or radar sensor), thermopiles stand out with particular advantages:

• In principle, uncooled and shutterless radiometric operations with extremely high refresh rates are possible (e.g. up to 160 Hz for the 8x8 array). In addition, there is no need (as is usually the case with bolometers) to interrupt detection to record signal drift or reference signals to compensate for the ambient temperature.
• Since thermopiles generate an electrical voltage through IR detection and therefore work passively, possible electronic consumption is only limited to the necessary additional electronics (ASIC, ADC, flash, etc.), which enables battery-powered applications.
• In comparison to radar sensors, which are also used to detect people, the principle of a completely passive sensor excludes any concerns about radiation exposure and additionally enables easier data processing without interference from other sensors.  Of course, the IR thermopile sensors cannot only detect people, but simultaneously can measure the temperatures of any other objects in the room without contact.


Products for various applications:

The large portfolio of possible optics and thus the scannable viewing angle (FOV) represents a unique selling point in the global market. A wide variety of applications can thus be covered, e.g. the detection of distant objects with a small viewing angle (FOV=10°) to wide-scale room surveillance (FOV =120°). In addition for the medium viewing angle range (FOV=30-50°), there are solutions ready by almost every array size. On top, an in-house optics simulation team enables quick and customer-specific adaptation if special optics are desired for a specific application.

Still, the portfolio goes far beyond temperature sensors as single, module (with digital and analog output) or array models.

Thermopiles (in combination with an infrared light source) are also utilized to measure the gas concentration of certain gases. The basic measurement principle is called Non-Dispersive Infra Red gas detection (NDIR), which is based on the absorption of infrared radiation at certain gas-specific wavelengths according to Lambert-Beer's law. The most common gases measured using this NDIR principle are carbon dioxide (CO2), methane (CH4), and hydrocarbons (HC). Gases such as carbon monoxide (CO) and nitrogen oxides (NO) can be detected, too.

MEMS Pirani vacuum sensors enable extreme accuracy compared to classic Pirani sensors equipped with a filament. They allow measurements in a pressure range from 1000 mbar (atmospheric pressure) down to 1E-3 mbar (HVS 04) and 10 mbar to 1E-5 mbar (HVS 03k). The miniature sensors are delivered in a small and robust TO-39/TO-46 metal housing. By installing the HVS 04 and HVS 03k together in a TO-8 housing, the entire pressure range can be covered.

A Glance into the future:

The use of modern AI algorithms empower IR sensors to automatically detect people. This becomes particularly interesting when data protection makes the use of normal cameras difficult. Low-resolution sensor arrays, such as the 16x16, 32x32, are the right choice, as faces cannot generally be identified. Applications extend from Ambient Assisted Living (AAL), for example in retirement homes or nursing homes, to monitoring public spaces/buildings.

The 45µm pixel size allows a kind of hybrid solution: installed in the WLP, the 60x40 array represents new standards in terms of sensitivity, size and speed for thermopile arrays. The sensor can be installed in the housing of its smaller brother (32x32), but is thanks to the SPI interface fast (21 Hz with 16 bit ADC resolution).  With 15 mW electrical power loss it has about ten times lower consumption than comparable bolometer models, which facilitates very effective battery-operated use. In addition, because of its number of pixels, it does not fall under the dual-use regulation.

In the version with 160x120 pixels, the sensor fits into a TO-8 housing. Like the 60x40, it has a flash memory for calibration data and works at approx. 10 Hz with 16 bit ADC resolution. Mass production is anticipated for the first quarter 2025.