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Electronic chips that are commercially available today are durable and long lasting. However, there is a great need for electronic systems that can lose the functionality and struc ture on demand, or after a certain amount of time. Transient electronics is an emerging technology field in which the func tionality of a chip can be altered or completely destroyed in a controlled manner. [1][2][3][4][5][6] Application areas of transient electronics include healthcare where electronic monitoring implants that can be resorbed in the body over time or a network of bio degradable sensors distributed in the environment that can pro vide data for a certain amount of time. [1][2][3][4][5][6][7][8][9][10][11] In today's digital age, the increasing dependence on information also makes us vulnerable to potential invasion of privacy and cyber security. Consider a scenario in which a hard drive is stolen, lost, or misplaced, which contains secured and valuable information. In such a case, it is important to have the ability to remotely destroy the sensitive part of the device (e.g., memory or processor) if it is not possible to regain it. Many emerging materials and even some traditional materials like silicon, aluminum, zinc oxide, tungsten, and magnesium, which are often used for logic processor and memory, show promise to be gradually dissolved upon exposure of various liquid medium. However, often these wet processes are too slow, fully destructive, and require assistance from the liquid materials and their suitable availability at the time of need. This study shows Joule heating effect induced thermal expansion and stress gradient between thermally expandable advanced polymeric material and flexible bulk monocrystalline silicon (100) to destroy highperformance solid state electronics as needed and under 10 s. This study also shows different stimuli-assisted smartphone-operated remote destructions of such complementary metal oxide semiconductor electronics.

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A technological platform is established for scalable flexible hybrid electronics (FHE) based on a novel fan-out wafer level packaging (FOWLP) methodology. Small dielets are embedded in flexible substrates we call FlexTrate TM . These dielets can be interconnected through high-density wirings formed in wafer-level processing. We demonstrate homogeneous integration of 625 (25 by 25) 1-mm-sqaure Si dielets and heterogeneous integration of GaAs and Si dielets with various thicknesses in a biocompatible polydimethylsiloxane (PDMS). In this work, 8-µm-pitch die-to-die interconnections are successfully implemented over a stress buffer layer (SBL) formed on the PDMS. In addition, coplanarity between the PDMS and embedded dielets, die shift concerned in typical die-first FOWLP, and the bendability of the resulting FlexTrate TM are characterized. Index Terms-flexible substrate, high-density interconnect, heterogeneous integration, Fan-Out Wafer-level Packaging (FOWLP), Polydimethylsiloxane (PDMS), and flexible hybrid electronics (FHE).

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