The response to ultraviolet illumination of ZnO nanoparticles deposited on LiNbO3 substrate was investigated using surface acoustic waves (SAWs) in the wide range of UV wavelengths from 280 to 375 nm. Deposition of ZnO nanoparticles caused a SAW transmission loss of 27 dB at 64 MHz due to the acoustoelectric attenuation. Acoustoelectric change in the SAW velocity by 3.78×10−4 under 375 nm illumination led to downshift in transmitted SAW phase by 5.5° at UV power density of 691 μW/cm2. The spectral measurements show the peak response at 345 nm with corresponding sensitivity on the order of 2.8 ppm/(μW/cm2).

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Various types of acoustic wave devices based on surface acoustic, acousto‐optic and photoacoustic effects are increasingly used for many biomedical applications. This paper reviews the basic physical phenomena of the acoustic wave propagation and photoacoustic and acousto‐optic interactions, which determine their sensing capabilities, and discusses recent applications of these devices in biology and medicine. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Propagation of surface acoustic waves in YZ LiNbO3 overlaid with graphene flakes has been investigated and its optical response to illumination by 633-nm light from a He-Ne laser was studied. The heating of the sample surface caused by optical absorption by the graphene led to a downshift in the transmitted SAW phase caused by the wave velocity's dependence on temperature. The proposed simple model based on optothermal SAW phase modulation was found to be in good agreement with the experimental results.

The response of the AlGaN based radio-frequency (rf) sensor to deep ultraviolet (UV) illumination was investigated. Illumination by UV light emitting diodes with wavelengths from 280 to 375 nm significantly decreased rf oscillator frequency due to change in the impedance of AlGaN-based metal-semiconductor-metal structure. The UV-induced frequency shift attains 400 kHz from the oscillator dark frequency of 144.5 MHz with the highest sensitivity of 40 kHz/(μW/cm2) at 280 nm wavelength and UV power density less than 7.4 μW/cm2. The AlGaN-based rf oscillator allows for a wireless visible-blind and solar-blind UV sensing.