Query: A Physically Transient Form of Silicon Electronics

Candidate papers:

abstract: Reversible Implants Silicon electronics are generally designed to be stable and robust it would be counterproductive if the key parts of your computer or cell phone slowly dissolved away while you were using it. In order to develop transient electronics for use as medical implants, Hwang et al. (p. 1640, see the cover) produced a complete set of tools and materials that would be needed to make standard devices. Devices were designed to have a specific lifetime, after which the component materials, such as porous silicon and silk, would be resorbed by the body. A platform of materials and fabrication methods furnishes resorbable electronic devices for in vivo use. A remarkable feature of modern silicon electronics is its ability to remain physically invariant, almost indefinitely for practical purposes. Although this characteristic is a hallmark of applications of integrated circuits that exist today, there might be opportunities for systems that offer the opposite behavior, such as implantable devices that function for medically useful time frames but then completely disappear via resorption by the body. We report a set of materials, manufacturing schemes, device components, and theoretical design tools for a silicon based complementary metal oxide semiconductor (CMOS) technology that has this type of transient behavior, together with integrated sensors, actuators, power supply systems, and wireless control strategies. An implantable transient device that acts as a programmable nonantibiotic bacteriocide provides a system level example.
author_names: Suk-Won Hwang

Hu Tao

Dae-Hyeong Kim

Huanyu Cheng

Jun-Kyul Song

Elliott Rill

Mark A Brenckle

Bruce J B Panilaitis

Sang Min Won

Yun-Soung Kim

Young Min Song

Ki Jun Yu

Abid Ameen

Rui Li

Yewang Su

Miaomiao Yang

David Lee Kaplan

Mitchell R Zakin

Marvin J Slepian

Yonggang Huang

Fiorenzo G Omenetto

John A Rogers
title: A Physically Transient Form of Silicon Electronics
venue: Science
year: 2012

abstract: A remarkable feature of modern silicon electronics is its ability to remain functionally and physically invariant, almost indefinitely for many practical purposes. Here, we introduce a siliconbased technology that offers the opposite behavior: it gradually vanishes over time, in a wellcontrolled, programmed manner. Devices that are 'transient' in this sense create application possibilities that cannot be addressed with conventional electronics, such as active implants that exist for medically useful timeframes, but then completely dissolve and disappear via resorption by the body. We report a comprehensive set of materials, manufacturing schemes, device components and theoretical design tools for a complementary metal oxide semiconductor (CMOS) electronics of this type, together with four different classes of sensors and actuators in addressable To whom correspondence should be addressed. jrogers@uiuc.edu; Fiorenzo.Omenetto@tufts.edu. *These authors contributed equally to this work. Supplementary Information is linked to the online version of the paper at www.nature.com/nature. Author Contributions S. W.H. H.T. D. H.K. F.G.O. J.A.R. designed the experiments; S. W.H. H.T. D. H.K. H.C. J. K.S. E.R. M.B. S. M.W. Y. S.K. K. J.Y. A.A. R. L. Y. S. Y.H. F.G.O. J.A.R. performed experiments and analyses; S. W.H. H.T. D.H.K. H.C. Y.H. F.G.O. J.A.R. wrote the paper. Competing Interests statement The authors declare that they have no competing financial interest. NIH Public Access Author Manuscript Science. Author manuscript; available in PMC 2013 September 30. Published in final edited form as: Science. 2012 September 28; 337(6102) 1640 1644. doi:10.1126/science.1226325. N IH PA Athor M anscript N IH PA Athor M anscript N IH PA Athor M anscript arrays, two options for power supply and a wireless control strategy. A transient silicon device capable of delivering thermal therapy in an implantable mode and its demonstration in animal models illustrate a system level example of this technology. An overarching goal in the development of nearly any new class of electronics is to achieve high performance operation in physical forms that undergo negligible change with time. Active and passive materials, device and circuit layouts and packaging strategies are each carefully formulated individually and then configured collectively to accomplish this outcome. The transient electronics technology introduced here involves similar attention to engineering design, but in the context of systems that physically disappear, in whole or in part, at prescribed times and with well defined rates. Use scenarios range from integration with living hosts (human/animal/insect/plant; on dwelling or in dwelling) to indoor/outdoor environments such as buildings, roadways or materiel. Enabled devices include medical monitors that fully resorb when implanted into the human body "bio resorbable" to avoid adverse long term effects, or communications systems that dissolve when exposed to water "eco resorbable" to prevent unwanted discovery. Other concepts involve circuits that incorporate strategic regions with timed transience, to affect controlled transformation in function. In this following, we present (1) a complete collection of transient electronic building blocks, including nand p channel silicon nanomembrane (NM) metal oxide field effect transistors (MOSFETs) and their integration into circuits that disappear or functionally transform, (2) sensors of light, temperature and strain, each of which uses functional materials and formats common to those for the electronics, (3) photovoltaic and inductive devices for power supply, (4) experimentally validated, analytical models of transience, suitable as design tools for engineered behaviours and (5) integrated examples in wirelessly controlled, bio resorbable devices that provide thermal therapy in an implantable form. Because this technology is based on silicon, it can exploit many modern, established aspects of device and circuit design, with operational characteristics that can match those of nontransient counterparts formed in the usual way on wafer substrates. This result, taken together with supporting technologies in sensors, power supply and wireless control, provides access to qualitatively more sophisticated capabilities than those available with recently reported forms of organic electronics in which certain constituent materials are water soluble [1 3] or simple non transient transistors formed on bio resorbable substrates [4] Figure 1a, b and S1 provide images and schematic diagrams of a demonstration platform for the technology. All of the components shown here, ranging from the inductors, capacitors, resistors, diodes, transistors, interconnects and crossovers, to the substrate and encapsulation layers disappear completely, through reactive dissolution by hydrolysis, as illustrated in the time sequence of images in Fig. 1c. This example of transient electronics uses magnesium (Mg) for the conductors, magnesium oxide (MgO) and silicon dioxide (SiO2) for the dielectrics, monocrystalline silicon (Si) NMs for the semiconductors, and silk (not only water soluble but also enzymatically degradable [4, 5] for the substrate and packaging material. The fabrication involves a combination of transfer printing (Si NMs) physical vapour deposition through fine line stencil masks (Mg, MgO, SiO2) and solution casting (silk) (See Methods and SI for details. In some cases, we used minute amounts of titanium to promote adhesion of Mg. Device fabrication was possible without this layer, although with somewhat lower yields in certain cases. The chemical reactions responsible for dissolution of each material appear in Fig. 1d. The Si NMs and layers of SiO2 are particularly important, due to their essential roles in high performance transistors, diodes, photodetectors, solar cells, temperature sensors, strain Hwang et al. Page 2 Science. Author manuscript; available in PMC 2013 September 30. N IH PA Athor M anscript N IH PA Athor M anscript N IH PA Athor M anscript gauges and other semiconductor devices, as described subsequently. For both, hydrolysis forms ortho silicic acid (Si(OH)4) whose water solubility is ~0.10 g/L at room temperature, as determined from studies of nanoporous silicon bodies [6 8] The NM geometry is important because it enables high performance devices and planar architectures, minimizes the amount of material that must be consumed during the transient step, and provides mechanics and processing options that are favourable for heterogeneous integration onto substrates such as silk [4] The second characteristic allows access to high rates of transience while avoiding solubility limits and potentially adverse biological responses, for applications where bio compatibility is important. A typical transistor described here involves less than ~1 mg of Si, which can be dissolved as Si(OH)4 in as little as 30 mL of water (or bio fluid) [8] Straightforward reductions in the dimensions of the devices could decrease even further the required amount of Si. For example, the mass of Si in the active region of a conventional MOSFET built on an ultrathin silicon on insulator wafer is ~10 fg, which corresponds to solubility in as little as ~300 fL [9] Figure 2a presents atomic force micrographs of a Si NM (3 x 3 mm) with thickness of 70 nm, collected at different stages of dissolution in phosphate buffer solution (PBS; pH of 7.4) at a physiologically relevant temperature (37 degC) to simulate transience by bio resorption (See Fig. S2 for different thicknesses of Si NM) The kinetics can be captured analytically using models of reactive diffusion (Fig. 2b; SI for details) [10 12] in which the rate limiting step is defined by diffusion of water and hydroxyl ions into the Si and reaction throughout the thickness direction y, according to [13 15] where D and k are the diffusivity for water and the reaction constant between silicon and PBS, respectively, and w is the concentration of water. Upon dissolution, the following equilibrium is formulated: Si +4H2O Si(OH)4+2H2, where the neutral silicic acid leaves the silicon surface by diffusion. In this model, the thickness of the Si NM (h) normalized by its initial thickness (h0) depends on the normalized time and reaction constant according to
author_names: Suk-Won Hwang

Hu Tao

Dae-Hyeong Kim

Huanyu Cheng

Jun-Kyul Song

Mark A Brenckle

Bruce J B Panilaitis

Sang Min Won

Yun-Soung Kim

Ki Jun Yu

Abid Ameen

Rui Li

Yewang Su

Miaomiao Yang

David Lee Kaplan

Mitchell R Zakin

Marvin J Slepian

Yonggang Huang

Fiorenzo G Omenetto

A John
title: A Physically Transient Form of Silicon Electronics With Integrated Sensors Actuators and Power Supply
year: 2013

abstract: Flexible transient photodetectors, a form of optoelectronic sensors that can be physically self destroyed in a controllable manner, could be one of the important components for future transient electronic systems. In this work, a scalable, device first, and bottom up thinning process enables the fabrication of a flexible transient phototransistor on a wafer compatible transferred silicon nanomembrane. A gate modulation significantly restrains the dark current to 10 12 A. With full exposure of the light sensitive channel, such a device yields an ultrahigh photo to dark current ratio of 107 with a responsivity of 1.34 A W 1 (l 405 nm) The use of a high temperature degradable polymer transient interlayer realizes on demand self destruction of the fabricated phototransistors, which offers a solution to the technical security issue of advanced flexible electronics. Such demonstration paves a new way for designing transient optoelectronic devices with a wafer compatible process.
author_names: Gongjin Li

Enming Song

Gaoshan Huang

Ruobing Pan

Qinglei Guo

Fei Ma

Bin Zhou

Zengfeng Di

Yongfeng Mei
title: Flexible Transient Phototransistors by Use of Wafer Compatible Transferred Silicon Nanomembranes.
venue: Small
year: 2018

abstract: This paper presents materials, device designs, and physical/electrical characteristics of a form of nanotube electronics that is physically transient, in the sense that all constituent elements dissolve and/or disperse upon immersion into water. Studies of contact effects illustrate the ability to use water soluble metals such as magnesium for source/drain contacts in nanotube based field effect transistors. High mobilities and on/off ratios in transistors that use molybdenum, silicon nitride, and silicon oxide enable full swing characteristics for inverters at low voltages ~5 V) and with high gains ~30) Dissolution/disintegration tests of such systems on water soluble sheets of polyvinyl alcohol demonstrate physical transience within 30 min.
author_names: Sung Hun Jin

Jongmin Shin

In-Tak Cho

Sang Youn Han

Dong Joon Lee

Chi Hwan Lee

Jongho Lee

John A Rogers
title: Solution processed single walled carbon nanotube field effect transistors and bootstrapped inverters for disintegratable, transient electronics
year: 2014

abstract: Transient electronics represents an emerging class of technology that exploits materials and/or device constructs that are capable of physically disappearing or disintegrating in a controlled manner at programmed rates or times. Inorganic semiconductor nanomaterials such as silicon nanomembranes/nanoribbons provide attractive choices for active elements in transistors, diodes and other essential components of overall systems that dissolve completely by hydrolysis in biofluids or groundwater. We describe here materials, mechanics, and design layouts to achieve this type of technology in stretchable configurations with biodegradable elastomers for substrate/encapsulation layers. Experimental and theoretical results illuminate the mechanical properties under large strain deformation. Circuit characterization of complementary metal oxide semiconductor inverters and individual transistors under various levels of applied loads validates the design strategies. Examples of biosensors demonstrate possibilities for stretchable, transient devices in biomedical applications.
author_names: Suk-Won Hwang

Chi Hwan Lee

Huanyu Cheng

Jae-Woong Jeong

Seung-Kyun Kang

Jae-Hwan Kim

Jiho Shin

Jian Yang

Zhuangjian Liu

Guillermo A Ameer

Yonggang Huang

John A Rogers
title: Biodegradable elastomers and silicon nanomembranes/nanoribbons for stretchable, transient electronics, and biosensors.
venue: Nano letters
year: 2015

abstract: Reactive dissolution and its effects on electrical conduction, morphological change and chemical transformation in thin films of Mg, AZ31B Mg alloy, Zn, Fe, W, and Mo in de ionized (DI) water and simulated body fluids (Hanks' solution pH 5 8) are systematically studied, to assess the potential for use of these metals in water soluble, that is, physically "transient" electronics. The results indicate that the electrical dissolution rates in thin films can be much different that traditionally reported corrosion rates in corresponding bulk materials. Silicon metal oxide field effect transistors (MOSFETs) built with these metals demonstrate feasibility for use in transient electronics.
author_names: Lan Yin

Huanyu Cheng

Shimin Mao

Richard T Haasch

Yuhao Liu

Xu Xie

Suk-Won Hwang

Harshvardhan Jain

Seung-Kyun Kang

Yewang Su

Rui Chun Li

Yonggang Huang

John A Rogers
title: Dissolvable Metals for Transient Electronics
year: 2014

abstract: Significance Bioresorbable electronic systems have the potential to create important new categories of technologies, ranging from temporary biomedical implants to environmentally benign, green consumer devices. The results presented here provide a collection of ideas that establish the foundations for a realistic technology of this type, in which state of the art silicon complementary metal oxide semiconductor foundries serve as the source of microscale, water soluble electronic components configured for rapid assembly and electrical interconnection on soft, biocompatible polymer substrates. Demonstrations in various high performance electronic systems illustrate the concepts, and fundamental studies establish the chemical kinetics and end products of dissolution in aqueous environments. Foundry based routes to transient silicon electronic devices have the potential to serve as the manufacturing basis for "green" electronic devices, biodegradable implants, hardware secure data storage systems, and unrecoverable remote devices. This article introduces materials and processing approaches that enable state of the art silicon complementary metal oxide semiconductor (CMOS) foundries to be leveraged for high performance, water soluble forms of electronics. The key elements are (i) collections of biodegradable electronic materials (e.g. silicon, tungsten, silicon nitride, silicon dioxide) and device architectures that are compatible with manufacturing procedures currently used in the integrated circuit industry, (ii) release schemes and transfer printing methods for integration of multiple ultrathin components formed in this way onto biodegradable polymer substrates, and (iii) planarization and metallization techniques to yield interconnected and fully functional systems. Various CMOS devices and circuit elements created in this fashion and detailed measurements of their electrical characteristics highlight the capabilities. Accelerated dissolution studies in aqueous environments reveal the chemical kinetics associated with the underlying transient behaviors. The results demonstrate the technical feasibility for using foundry based routes to sophisticated forms of transient electronic devices, with functional capabilities and cost structures that could support diverse applications in the biomedical, military, industrial, and consumer industries.
author_names: Jan-Kai Chang

Hui Fang

Christopher A Bower

Enming Song

Xinge Yu

John A Rogers
title: Materials and processing approaches for foundry compatible transient electronics
venue: Proceedings of the National Academy of Sciences
year: 2017

abstract: Areas of application that span almost every class of microsystems technology, from electronics to energy storage devices to chemical/biochemical sensors, can benefit from options in engineering designs that exploit 3D micro/nanostructural layouts. Recently developed methods for forming such systems exploit stress release in prestretched elastomer substrates as a driving force for the assembly of 3D functional microdevices from 2D precursors, including those that rely on the most advanced functional materials and device designs. Here, concepts that expand the options in this class of methods are introduced, to include 1) component parts built with physically transient materials to allow triggered transformation of 3D structures into other shapes and 2) mechanical interlocking elements composed of female type lugs and maletype hooks that activate during the assembly process to irreversibly "lock in" the 3D shapes. Wireless electronic devices demonstrate the utility of these ideas in functional systems.
author_names: Haiwen Luan

Daniel Franklin

Wubin Bai

Yihui Zhang
title: Transformable, Freestanding 3D Mesostructures Based on Transient Materials and Mechanical Interlocking
venue: Advanced Functional Materials
year: 2019

abstract: Transient forms of electronics, systems that disintegrate, dissolve, resorb, or sublime in a controlled manner after a well defined operating lifetime, are of interest for applications in hardware secure technologies, temporary biomedical implants, "green" consumer devices and other areas that cannot be addressed with conventional approaches. Broad sets of materials now exist for a range of transient electronic components, including transistors, diodes, antennas, sensors, and even batteries. This work reports the first examples of transient light emitting diodes (LEDs) that can completely dissolve in aqueous solutions to biologically and environmentally benign end products. Thin films of highly textured ZnO and polycrystalline Mo serve as semiconductors for light generation and conductors for transparent electrodes, respectively. The emitted light spans a range of visible wavelengths, where nanomembranes of monocrystalline silicon can serve as transient filters to yield red, green, and blue LEDs. Detailed characterization of the material chemistries and morphologies of the constituent layers, assessments of their performance properties, and studies of their dissolution processes define the underlying aspects. These results establish an electroluminescent light source technology for unique classes of optoelectronic systems that vanish into benign forms when exposed to aqueous conditions in the environment or in living organisms.
author_names: Di Lu

Tzu-Li Liu

Jan-Kai Chang

Dongsheng Peng

Yanwen Zhang

Jiho Shin

Tao Hang

Wubin Bai

Quansan Yang

John A Rogers
title: Transient Light Emitting Diodes Constructed from Semiconductors and Transparent Conductors that Biodegrade Under Physiological Conditions.
venue: Advanced materials
year: 2019

abstract: Recent advances in materials chemistry establish the foundations for unusual classes of electronic systems, characterized by their ability to fully or partially dissolve, disintegrate, or otherwise physically or chemically decompose in a controlled fashion after some defined period of stable operation. Such types of "transient" technologies may enable consumer gadgets that minimize waste streams associated with disposal, implantable sensors that disappear harmlessly in the body, and hardware secure platforms that prevent unwanted recovery of sensitive data. This second area of opportunity, sometimes referred to as bioresorbable electronics, is of particular interest due to its ability to provide diagnostic or therapeutic function in a manner that can enhance or monitor transient biological processes, such as wound healing, while bypassing risks associated with extended device load on the body or with secondary surgical procedures for removal. Early chemistry research established sets of bioresorbable materials for substrates, encapsulation layers, and dielectrics, along with several options in organic and bio organic semiconductors. The subsequent realization that nanoscale forms of device grade monocrystalline silicon, such as silicon nanomembranes (m Si NMs, or Si NMs) undergo hydrolysis in biofluids to yield biocompatible byproducts over biologically relevant time scales advanced the field by providing immediate routes to high performance operation and versatile, sophisticated levels of function. When combined with bioresorbable conductors, dielectrics, substrates, and encapsulation layers, Si NMs provide the basis for a broad, general class of bioresorbable electronics. Other properties of Si, such as its piezoresistivity and photovoltaic properties, allow other types of bioresorbable devices such as solar cells, strain gauges, pH sensors, and photodetectors. The most advanced bioresorbable devices now exist as complete systems with successful demonstrations of clinically relevant modes of operation in animal models. This Account highlights the foundational materials concepts for this area of technology, starting with the dissolution chemistry and reaction kinetics associated with hydrolysis of Si NMs as a function of temperature, pH, and ion and protein concentration. A following discussion focuses on key supporting materials, including a range of dielectrics, metals, and substrates. As comparatively low performance alternatives to Si NMs, bioresorbable organic semiconductors are also presented, where interest derives from their intrinsic flexibility, low temperature processability, and ease of chemical modification. Representative examples of encapsulation materials and strategies in passive and active control of device lifetime are then discussed, with various device illustrations. A final section outlines bioresorbable electronics for sensing of various biophysical parameters, monitoring electrophysiological activity, and delivering drugs in a programmed manner. Fundamental research in chemistry remains essential to the development of this emerging field, where continued advances will increase the range of possibilities in sensing, actuation, and power harvesting. Materials for encapsulation layers that can delay water diffusion and dissolution of active electronics in passively or actively triggered modes are particularly important in addressing areas of opportunity in clinical medicine, and in secure systems for envisioned military and industrial uses. The deep scientific content and the broad range of application opportunities suggest that research in transient electronic materials will remain a growing area of interest to the chemistry community.
author_names: Seung-Kyun Kang

Jahyun Koo

Yoon Kyeung Lee

John A Rogers
title: Advanced Materials and Devices for Bioresorbable Electronics.
venue: Accounts of chemical research
year: 2018