Localized Microfluidic Mixer Using Planar Fresnel Type GHz Ultrasonic Transducer

摘要

We present a microfluidic mixer that uses focused GHz ultrasonic waves to create streaming vortices in an otherwise laminar fluidic flow. Owing to high absorption and small wavelength at gigahertz., the mixing activity is highly localized. The ultrasonic focusing is achieved by means of an aluminum nitride based bulk acoustic wave transducer placed in a Fresnel lens configuration on a silicon substrate. The transducer is planar and is fabricated with a CMOS compatible process with no thin-film release steps. Further., the transducer is on the opposite side of fluidics thereby enabling easier integration of transducers and fluidics in a distributed manner. Microfluidic mixing of blue dye and water was observed with 90% efficiency., when the transducer was driven by a 1.06GHz continuous wave RF signal of 20dBm power.