A digital microfluidic biochip (DMB) is an attractive platform for automating laboratory procedures in microbiology. However, a major problem associated with today's DMBs is the risk of cross-contamination due to undesirable fouling of the electrode surface, i.e., droplet materials stick to the surface. To overcome the above problem, a contactless liquid-handling biochip technology referred to as acoustofluidics has recently been proposed, and droplet manipulations on acoustofluidic biochips have also been experimentally demonstrated. In order to ensure robust fluidic operations and high confidence in the outcome of biochemical experiments, acoustofluidic biochips must be adequately tested before they are used for bioassay execution. This paper presents the first approach for testing of an acoustofluidic biochip that includes an array of interdigital transducers (IDTs). We first present structural test techniques to evaluate the pass/fail status of each IDT, and identify the type of fault if it fails. In order to ensure correct operation of functional units, e.g., mixers and routers, we also present functional test techniques to address fundamental acoustofluidic operations such as droplet transportation and droplet mixing. We evaluate the proposed test methods using experiments on fabricated acoustofluidic biochips.
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