SGP 30 - The Game Changing Metal Oxide Semiconductor Sensor

The First Siloxane Resistant Metal Oxide Semiconductor (MOS)VOC Sensor

Siloxanes, in traditional metal oxide semiconductor (MOS) sensors (which is of low molecular weight), can easily be thermally decomposed to silicone dioxide (SiO2) by the working temperature of sensor sensing element. SiO2 would cause deactivation of the catalyst in the sensing element and therefore, decrease the sensor’s resistance in the air, alter its sensitivity to target gas and increase response time. Changes are irreversible, long term exposure to siloxanes makes sensor non-functional.

Siloxanes contain for example:
• mobile phone covers
• indoor environments
• the most abundant VOC emitted by human (Tang et al, Environ. Sci. Technol. Left (2015))

Sensirion’s proprietary metal-oxide technology and multi-pixel platform provide the SGP30 with an unmatched robustness against siloxanes resulting in a unique long-term stability and accuracy.

The First MOS Sensor with accuracy specification

Every SGP30 sensor is calibrated during production. Only sensors fulfilling the specification reach customers.

The First MOS Sensor with On-Chip Signal Processing

SGP30 contains four MOS sensing elements in one package heated to optimal temperature by temperature-regulated micro heater. Elements are sensitive to VOC and Hydrogen. Sensor measures total VOC concentration and calculates CO2 concentration by measuring concentration of Hydrogen. It has built-in dynamic baseline correction algorithm. Sensor provides total VOC and CO2eq values through I2C bus.

The SGP30 doesn’t measure CO2 concentration; it calculates concentration based on the Hydrogen concentration measurement. Human breath contains significant concentrations of Hydrogen (approx. 10 ppm) and CO2 (approx. 4%). Humans are the only major source of Hydrogen and CO2 in indoor environments. In such a case, it is possible to calculate CO2 concentration from measured Hydrogen concentration. The Hydrogen - CO2 correlation is not perfect due to variations between individuals, but good enough to control ventilation or air purifiers.

Why Measure VOC?

30% of new buildings have poor indoor air quality (IAQ), 20% of individuals complain about temporary or chronic pains due to poor IAQ (Sick Building Syndrome), increased VOC values have a significant negative effect on cognitive abilities like strategic thinking and decision making etc.
The German Health Department defines TVOC levels as shown in the table below. The TVOC levels and the corresponding recommendations are based on the results of a large number of controlled exposure studies that established a relationship between increased TVOC levels and adverse health effects.

For further information about Sensirion products, please look at our Sensirion web pages or contact us at sensirion@soselectronic.com