Baban Navajit Singh, Zhou Jiarui, Elkhoury Kamil, Bhattacharjee Sukanta, Vijayavenkataraman Sanjairaj, Gupta Nikhil, Song Yong-Ak, Chakrabarty Krishnendu, Karri Ramesh
Division of Engineering, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates.
Department of Computer Science and Engineering, Indian Institute of Technology Guwahati, Guwahati, India.
Sci Rep. 2024 Aug 27;14(1):19806. doi: 10.1038/s41598-024-70703-0.
Flow-based microfluidic biochips (FMBs) are widely used in biomedical research and diagnostics. However, their security against potential material-level cyber-physical attacks remains inadequately explored, posing a significant future challenge. One of the main components, polydimethylsiloxane (PDMS) microvalves, is pivotal to FMBs' functionality. However, their fabrication, which involves thermal curing, makes them susceptible to chemical tampering-induced material degradation attacks. Here, we demonstrate one such material-based attack termed "BioTrojans," which are chemically tampered and optically stealthy microvalves that can be ruptured through low-frequency actuations. To chemically tamper with the microvalves, we altered the associated PDMS curing ratio. Attack demonstrations showed that BioTrojan valves with 30:1 and 50:1 curing ratios ruptured quickly under 2 Hz frequency actuations, while authentic microvalves with a 10:1 ratio remained intact even after being actuated at the same frequency for 2 days (345,600 cycles). Dynamic mechanical analyzer (DMA) results and associated finite element analysis revealed that a BioTrojan valve stores three orders of magnitude more mechanical energy than the authentic one, making it highly susceptible to low-frequency-induced ruptures. To counter BioTrojan attacks, we propose a security-by-design approach using smooth peripheral fillets to reduce stress concentration by over 50% and a spectral authentication method using fluorescent microvalves capable of effectively detecting BioTrojans.
基于流的微流控生物芯片（FMBs）广泛应用于生物医学研究和诊断。然而，它们对潜在的物质层面网络物理攻击的安全性仍未得到充分探索，这构成了未来的一项重大挑战。主要组件之一聚二甲基硅氧烷（PDMS）微阀对于FMBs的功能至关重要。然而，其制造过程涉及热固化，这使得它们容易受到化学篡改引起的材料降解攻击。在此，我们展示了一种这样的基于材料的攻击，称为“生物木马”，即经过化学篡改且光学上隐形的微阀，可通过低频驱动使其破裂。为了对微阀进行化学篡改，我们改变了相关的PDMS固化比例。攻击演示表明，固化比例为30:1和50:1的生物木马阀在2Hz频率驱动下迅速破裂，而固化比例为10:1的正宗微阀即使在相同频率下驱动2天（345,600个循环）后仍保持完好。动态机械分析仪（DMA）结果及相关有限元分析表明，生物木马阀储存的机械能比正宗微阀多三个数量级，使其极易受到低频引起的破裂。为了应对生物木马攻击，我们提出一种设计安全方法，使用光滑的周边圆角将应力集中降低50%以上，以及一种光谱认证方法，使用能够有效检测生物木马的荧光微阀。
