Thermal transpiration

In collaboration with EPFL, we have developed a silica based aerogel Knudsen Pump prototype by combining a low temperature co-fired ceramic technology and sodium silicate based aerogels. A temperature difference applied by resistive heating of the ceramic substrate and a flow rate density ~38 µl min-1 mm-2 was reached. A comparison with other Knudsen pump membranes shows outstanding performance [1].

Recently, based on a breakthrough 3D printing technology, our group was able to print a prototype membranes with a top-layer containing manganese oxide nanoflakes. The MnO2 serves as a dual-functional light absorbers for the efficient photo-thermal conversion to reach a pumping flow rate of 20 µl min-1 mm-2, and in addition, the catalytic degradation of VOCs [2]. Furthermore, the processing, pore formation and properties (pumping and catalysis) correlations in an aerogel Knudsen Pump system were explored, and various aerogel materials with complementary properties have been developed [3].
[1] S. Zhao et al., Dimensional and Structural Control of Silica Aerogel Membranes for Miniaturized Motionless Gas Pumps, ACS Appl. Mater. Interfaces 7(33) (2015) 18803-18814. [2] S. Zhao et al., Additive manufacturing of silica aerogels. Nature, 2020, 584 (7821):387-392. [3] S. Drdova, S. Zhao et al.. Biomimetic Light‐Driven Aerogel Passive Pump for Volatile Organic Pollutant Removal. Advanced Science, 2022, 2105819.
Dr. Shanyu Zhao

Dr. Shanyu Zhao
Group leader in Functional Aerogel Materials Group

Phone: +41 58 765 4244