Dependability is an important attribute for microfluidic biochips that are used for safety-critical applications such as point-of-care health assessment, air-quality monitoring, and food-safety testing. Therefore, these devices must be adequately tested after manufacture and during bioassay operations. Moreover, since disposable biochips are being targeted for a highly competitive and low-cost market segment, test and diagnosis methods should be inexpensive, quick, and effective. We propose a cost-effective testing methodology referred to as “parallel scan-like test”, and a rapid diagnosis method based on test outcomes, for droplet-based microfluidic devices. The proposed method allows testing using parallel droplet pathways in both on-line and off-line scenarios. The diagnosis outcome can be used to reconfigure a droplet-based biochip such that faults can be easily avoided, thereby enhancing chip yield and defect tolerance. We evaluate the proposed test and diagnosis methods usin...