Surface acoustic waves as the energy source for droplet-based micro-reactor with oil encapsulation

Summary form only given. A SAW-based micro-reactor for biochemical assay using droplets encapsulated inside oil droplets is reported. Two interdigital transducers (IDTs) with 35 finger pairs, apertures of 4.32 mm, and a center frequency of 27.7 MHz were fabricated on a 127.86° rotated Y-cut X-propagating LiNbO₃ substrate. Biochemical reagent droplets encapsulated in oil droplets, which the reagent evaporation rate was greatly reduced, were pipetted onto the substrate. SAW generated by the IDTs heated the oil droplets and then raised the temperature of the reagent droplets. A color development reaction of starch has been tested. Gray value of an image has been used to analyze reaction response. Results show that the reaction velocity is accelerated with increased RF signal power fed onto the IDTs. The micro-reactor has the potential to systematically perform economical biochemical analysis on a chip.