Acoustic mixer using low frequency vibration for biological and chemical applications

• We made an acoustic mixer using low frequency vibration.
• We tested the device on a 400 nL microdroplet matrix.
• We used conventionally immiscible liquids and demonstrated their homogenization using acoustic mixing.
• The acoustic energy creates a heating effect in liquid that depends essentially on the excitation power.
• In order to use the transducer in the biological domain, we determined the mixer excitation power which has a negligible thermal effect.

Liquid mixing at micro-scale is considered a challenge which is even tougher to overcome in the case of discrete microfluidic. Many researchers have developed strategies and tried to be pioneer in mixing solutions for lab on chip. In this paper, we present a parallel microdroplet mixer based on acoustic field generation using a low frequency vibration (up to few hundreds of kilohertz). This device can be used for lab on chip applications, since the liquid characteristics are not disturbed by the plugged energy and involve relatively simple microfabrication techniques. We designed, fabricated, evaluated, presented experiments showing the microdroplet active mixing, and investigated the thermal effect of the created acoustic energy.