Printed electronics (PE) enables disruptive applications in wearables, smart sensors, and healthcare since it provides mechanical flexibility, low cost, and on-demand fabrication. The progress in PE raises trust issues in the supply chain and vulnerability to reverse engineering (RE) attacks. Recently, RE attacks on PE circuits have been successfully performed, pointing out the need for countermeasures against RE, such as camouflaging. In this article, we propose a printed camouflaged logic cell that can be inserted into PE circuits to thwart RE. The proposed cell is based on three components achieved by changing the fabrication process that exploits the additive manufacturing feature of PE. These components are optically look-alike, while their electrical behaviors are different, functioning as a transistor, short, and open. The properties of the proposed cell and standard PE cells are compared in terms of voltage swing, delay, power consumption, and area. Moreover, the proposed camouflaged cell is fabricated and characterized to prove its functionality. Furthermore, numerous camouflaged components are fabricated, and their (in)distinguishability is assessed to validate their optical similarities based on the recent RE attacks on PE. The results show that the proposed cell is a promising candidate to be utilized in camouflaging PE circuits with negligible overhead.

中文翻译：

---

一种对抗印刷电子电路逆向工程的印刷伪装单元

印刷电子 (PE) 能够在可穿戴设备、智能传感器和医疗保健领域实现颠覆性应用，因为它提供机械灵活性、低成本和按需制造。PE 的进展引发了供应链中的信任问题以及逆向工程 (RE) 攻击的脆弱性。最近，RE 对 PE 电路的攻击已经成功执行，这表明需要针对 RE 采取伪装措施。在本文中，我们提出了一种可插入 PE 电路以阻止 RE 的印刷伪装逻辑单元。所提出的电池基于三个组件，通过改变利用 PE 的增材制造特征的制造工艺实现。这些组件在光学上看起来很相似，但它们的电气特性却不同，分别充当晶体管、短路和开路。在电压摆幅、延迟、功耗和面积方面比较了所提出的单元和标准 PE 单元的特性。此外，所提出的伪装电池被制造和表征以证明其功能。此外，制造了许多伪装组件，并评估了它们的（不）可区分性，以根据最近对 PE 的 RE 攻击来验证它们的光学相似性。结果表明，所提出的单元是一个很有前途的候选者，可用于伪装开销可忽略不计的 PE 电路。并且根据最近对 PE 的 RE 攻击，评估它们的（非）可区分性以验证它们的光学相似性。结果表明，所提出的单元是一个很有前途的候选者，可用于伪装开销可忽略不计的 PE 电路。并且根据最近对 PE 的 RE 攻击，评估它们的（非）可区分性以验证它们的光学相似性。结果表明，所提出的单元是一个很有前途的候选者，可用于伪装开销可忽略不计的 PE 电路。