On-Line Error Detection in Digital Microfluidic Biochips

Digital microfluidic technology is being increasingly used for implementing a lab-on-a-chip with many life-critical applications. Testing of these biochips is thus indispensable not only after manufacture, but also during in-field operation. To keep the product cost (including both design and test) low for disposable biochips, efficient on-line test techniques are desirable. All previous on-line test mechanisms interleave testing and the target bioassay protocol, but they involve overhead such as use of separate test droplet(s) and increased completion time. In this paper, we propose a simple on-line error-detection methodology that can be performed concurrently with the normal operation of the system with no or little extra effort. The proposed procedure does not require any test droplet. In the case of incorrect operation, the error is detected on or before the completion of the bioassay. The main objective of the proposed strategy is to ensure the correctness of the executed assay on-chip and not to guarantee the absence of a defect in the chip. The given assay protocol is assumed to be executed correctly if the on-line procedure finishes with success. The assay is aborted as soon as an error is detected, thereby saving costly sample/reagents. Moreover, the scheme can be easily adopted to enhance diagnosis.