Fig. 4: Optoacoustic sensing of the diffusion dynamics in microfluidics. | Nature Communications

Fig. 4: Optoacoustic sensing of the diffusion dynamics in microfluidics.

From: High spatiotemporal resolution optoacoustic sensing with photothermally induced acoustic vibrations in optical fibres

Fig. 4

a Schematic diagram of the Y-shaped microfluidic diffuser. Two miscible liquids flow over the common path and create an acoustic impedance gradient at their interface. b Optoacoustic sensing result of the diffusion dynamics over 35 s. Surface plot: measured acoustic impedance. c Surface plot of the acoustic spectrum and d acoustic impedance Z across the liquid interface, measured at time t = 7 s. The two dashed lines represent the impedances of the two liquids. e Frequency spectrum of the diffusion interface shift. The periodic shift at 1.07 Hz is a result of the pulsed actuation of the stepper motor. f Subsequent snapshots of the impedance map after turning on the water path. g Sensing length extension to 6 mm by multiplexing three sensors. WDM, Wavelength-division multiplexer.

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