• Beyssen, Denis
• Roux-Marchand, Thibaut
• Elmazria, Omar
• Sarry, Frederic
• Grandemange, Stéphanie

Abstract

In this paper, we report a specific Rayleigh-Surface Acoustic Wave (R-SAW) structure for discrete microfluidic application, especially for Polymerase Chain Reaction (PCR) to replicate DeoxyriboNucleic Acid (DNA) strands. We present a multilayer device which allows to heat microdroplets beyond the maximum temperature of the PCR. For this, we buried Interdigital Transducer (IdT) under a sputtered Aluminium Nitride (AlN) layer to electrically insulate, enhance the electromechanical couling factor and the thermal conductivity. In this way, the droplet can be deposited directly on the IdT leading to minimize all losses. Moreover, streaming in microdroplet is achieved during heating. This would promote the PCR reaction even with viscous liquids which is not possible with common thermocycler where conduction appears mainly. We have studied the heating of 10μL microdroplets with many viscosities as a function of electrical power and AlN thickness. Then, we explored the compatibility of R-SAWs and the biological species of PCR to conclude the possibility to use R-SAW for PCR applications. With the proposed multilayer device, the microdroplet has reached a temperature of more than 95°C with 3.2W which is higher than the maximum temperature required for PCR. Theses temperatures is achieved with viscous liquid above 10.8mPa.s. Then, we have shown that R-SAWs are compatible with PCR biological species whatever the time duration of irradiation and the wave’s power. For this, we have irradiated microdroplets containing all the necessary mixture of PCR before doing classical PCR and quantification. We conclude that our specific R-SAW device can be used for DNA replication by PCR.

Topics

• impedance spectroscopy
• surface
• aluminium
• nitride
• thermal conductivity