A Survey on Security of Digital Microfluidic Biochips: Technology, Attack, and Defense

As an emerging lab-on-a-chip technology platform, digital microfluidic biochips (DMFBs) have been widely used for executing various laboratory procedures in biochemistry and biomedicine such as gene sequencing and near-patient diagnosis, with the advantages of low reagent consumption, high precision, and miniaturization and integration. With the ongoing rapid deployment of DMFBs, however, these devices are now facing serious and complicated security challenges that not only damage their functional integrity but also affect their system reliability. In this article, we present a systematic review of DMFB security, focusing on both the state-of-the-art attack and defense techniques. First, the overall security situation, the working principle, and the corresponding fabrication technology of DMFBs are introduced. Afterwards, existing attack approaches are divided into several categories and discussed in detail, including denial of service, intellectual property piracy, bioassay tampering, layout modification, actuation sequence tampering, concentration altering, parameter modification, reading forgery, and information leakage. To prevent biochips from being damaged by these attack behaviors, a number of defense measures have been proposed in recent years. Accordingly, we further classify these techniques into three categories according to their respective defense purposes, including confidentiality protection, integrity protection, and availability protection. These measures, to varying degrees, can provide effective protection for DMFBs. Finally, key trends and directions for future research that are related to the security of DMFBs are discussed from several aspects, e.g., manufacturing materials, biochip structure, and usage environment, thus providing new ideas for future biochip protection.