Here we report a new study,on the effect of input excitation frequency by a surface acoustic wave (SAW) device on the droplet displacement for use in microfluidics.Most of the current literatures had studied the effect of SAW excitation power on pumping.Apart from input power,frequency of the acoustic wave also is a key parameter for enhancing the droplet actuation.As reported in [1] a recent literature,the effect of frequency on acoustic streaming was discussed.Current literature,does not provide information about the effect of frequency on droplet pumping phenomenon.The droplet velocity as observed experimentally,decreases with increasing SAW excitation frequency (Fig 2a).This can be attributed towards increasing acoustic absorption coefficient per unit length scale of Rayleigh wave with rising frequency given by [2].As the input excitation frequency increases the smaller the energy which reaches the droplet top free surface,which results in lower droplet deformation and hence reduces the asymmetry in the droplet which is regarded as the cause for droplet displacement [3].The effect of input voltage excitation on droplet velocity is non-linear (Fig 2b).Moreover,it shows an increased velocity for a droplet of size 1μL as compared to 0.5μL,which can be attributed to an optimum droplet size to the attenuation length as discussed in [4].The SAW devices were fabricated on a 1280- rotated Y-cut X-propagating lithium niobate substrate (LiNbO3) using standard lithographic procedure (Fig 1a).FEM simulation using ANSYS was performed (Fig 3) to design the SAW device (IDT spacing).Fig 1b,shows the reflection spectra (S11) for the devices after fabrication.Pulsed RF power was applied to avoid the problems of substrate heating and droplet evaporation.These results can be used to optimize the device designs,by considering the frequency rather than the amplitude alone.Higher droplet velocities at lower power could be achieved,which forms the ideal requirement for a portable lab-on-chip device.