Cellulose aerogel material acts as three-in-one sensor

Described in the journal Advanced Science, the sensor could reduce the complexity and cost of IoT solutions and have applications across several industries, including robotics, healthcare and security. Its underlying material is made by combining cellulose nanofibres with the conducting polymer PEDOT:PSS and freeze-drying the mixture in a vacuum. Adding a substance known as polysilane causes the resulting aerogel to become elastic.

The material conducts ions and electrons, exploiting the subsequent thermoelectric effect whereby electrons move from the cold side of the material to the warm side. This creates a voltage difference that can be measured. Increased pressure causes a fall in resistance and electrons flow more readily. Similarly, the larger the temperature difference between the warm and cold sides, the higher the voltage developed.

Humidity also affects the material, determining how rapidly the ions move from the warm side to the cold one. If the humidity is zero, no ions are transported. A key innovation from the Linköping scientists was devising a method to determine the effect of each parameter independently in order to get clean readings.