Humidity-sensitive SAW device based on TPPS4 nanostrip structure

The response to ambient humidity of the surface acoustic wave devices based on TPPS₄ -LiNbO₃ structures has been experimentally studied. Both monomer and self assembled J-aggregates nanostrip TPPS₄ films were used. The SAW delay-line transmission and SAW oscillator frequency exhibit considerable sensitivity to ambient humidity. With growing humidity, the transmission loss of the SAW delay-line increases, and the SAW oscillator frequency decreases. Typically, the monomer films are more sensitive to humidity changes than the aggregate films. In the SAW frequency range 50-300 MHz, the structure response noticeably increases with frequency increase. The TPPS₄ based SAW device exhibited a very fast response to abrupt humidity changes with a characteristic time of not more than 0.6 sec.