sentences:  [Figure 1] The diameter of the droplet scales inversely with the frequency of the acoustic energy—higher frequencies produce smaller droplets.Unlike other liquid transfer devices, no pipette tips, pin tools, or nozzles touch the source liquid or destination surfaces.Liquid transfer methods that rely on droplet formation through an orifice, e.g., disposable tips or capillary nozzles, invariably lose precision as the transfer volume decreases.