Fig. 6

Dynamic monitoring of liquids by liquid-interactive ferroelectric sound. a A photograph of an liquid-interactive ferroelectric sound (LIFS) alternative current (AC) device with three in-plane PEDOT:PSS electrodes for monitoring the velocity of a liquid in microfluidic channels. Sound amplitude monitored with time when deionised water passed through the microfluidic channel. b A photograph of an LIFS AC device with two in-plane PEDOT:PSS electrodes for monitoring the flow of human serum in a capillary channel similar in size to the human capillaries. Sound amplitude monitored with time when the serum passed through the capillary. c A photograph of an LIFS AC device with two in-plane PEDOT:PSS electrodes for monitoring two different liquids in a microfluidic channel. Alternating flows of deionised water and mineral oil were developed with two injection systems. The characteristic sound amplitudes for deionised water and mineral oil were precisely monitored with time. All the devices were operated at the AC frequency and voltage of 20 kHz and 100 V, respectively