Integration of Localized Surface Plasmon Resonance Sensor on Surface Acoustic Wave Device

When a localized surface plasmon resonance (LSPR) sensor is fabricated on a surface acoustic wave (SAW) propagating surface, transportation of a droplet by the SAW and measurement of it by the LSPR are possible. It is important to know the effect of a SAW on the LSPR sensor. Especially, it is necessary to clarify the effect of acoustic streaming caused by the SAW in a liquid on the LSPR sensor. In this paper, two sample liquids, distilled or ultrapure waters, are placed on the SAW device, and the LSPR sensor response is monitored during SAW excitation. Whereas the LSPR sensor responses are stable for ultrapure water, those for distilled water are variable. Comparison with the calculation results reveals that the reason for this is the cavitation effect caused by acoustic streaming. Moreover, to avoid the cavitation effect, it is found that the applied voltage to the interdigital transducer for exciting SAW must be less than 20 V.