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Origami, the art of paper folding, has emerged as a versatile technique for crafting intricate 3D structures from 2D sheets. Combined with the magnetic actuation, origami paper becomes the building blocks for cost‐effective, wirelessly controllable magnetic robots. Herein, a biodegradable magnetic paper with excellent formability and recyclability is developed, facilitating its convenient utilization and disposal. The programable magnetic paper, fabricated with specific magnetization and crease patterns, enables the transformation of 2D sheets into predetermined 3D structures. Leveraging the lightweight and pliable nature of paper‐based materials, exceptional control of origami robots with fast response is demonstrated, enabling a wide range of locomotion. Furthermore, the paper‐based approach enables the incorporation of electronic functionality into magnetic actuators. By introducing conductive nanoparticles into magnetic paper, an electrically conductive substance is created. Constructing electronic circuits and integrating electronic components onto the paper‐based printed circuit board platform enables the repairing of broken circuits inside complicated equipment and optical sensing of surrounding environments in conjunction with locomotive robots. The origami robots have a huge potential to be facilitated in diverse fields with various functions, demonstrating complex locomotion, and integrating chemical, optical, thermal, and mechanical sensors for monitoring environmental conditions in hard‐to‐reach locations. The array of possibilities holds significant promise for the widespread application of these origami magnetic robots across a diverse spectrum of research fields in soft robotics.

Abstract Achieving optimal camouflage in an aquatic environment necessitates the ability to modulate transmittance in response to the surrounding obscurity and potential threats. This adaptation involves a dynamic transition from transparency to a deep-blue color, especially in low-light or dark situations. Such a strategy promotes a seamless assimilation with the surroundings, enabling the absorption of searchlights and, subsequently, diminishing the risk of detection by predators. Therefore, the presence of sophisticated mechanisms that facilitates stable and efficient control of transmittance is imperative, enabling smooth transition between transparent and deep-blue hues within the aquatic environment. This study presents nature-inspired programmable camouflage system that integrates an electrochromic display as the primary transmittance change element and a wireless base module for power and data transmission. Such technology offers a robust and flexible construction, ensuring stable operation as demonstrated through mechanical-fatigue experiments and quantitative simulation. A custom circuit and a power-control software package enable active control of multiple electrochromic displays while submerged in water.

Abstract Magnetic resonance imaging (MRI) is widely used in clinical care and medical research. The signal‐to‐noise ratio (SNR) in the measurement affects parameters that determine the diagnostic value of the image, such as the spatial resolution, contrast, and scan time. Surgically implanted radiofrequency coils can increase SNR of subsequent MRI studies of adjacent tissues. The resulting benefits in SNR are, however, balanced by significant risks associated with surgically removing these coils or with leaving them in place permanently. As an alternative, here the authors report classes of implantable inductor–capacitor circuits made entirely of bioresorbable organic and inorganic materials. Engineering choices for the designs of an inductor and a capacitor provide the ability to select the resonant frequency of the devices to meet MRI specifications (e.g., 200 MHz at 4.7 T MRI). Such devices enhance the SNR and improve the associated imaging capabilities. These simple, small bioelectronic systems function over clinically relevant time frames (up to 1 month) at physiological conditions and then disappear completely by natural mechanisms of bioresorption, thereby eliminating the need for surgical extraction. Imaging demonstrations in a nerve phantom and a human cadaver suggest that this technology has broad potential for post‐surgical monitoring/evaluation of recovery processes.

Abstract Variations in parameters associated with the ambient environment can introduce noise in soft, body-worn sensors. For example, many piezoresistive pressure sensors exhibit a high degree of sensitivity to fluctuations in temperature, thereby requiring active compensation strategies. The research presented here addresses this challenge with a multilayered 3D microsystem design that integrates four piezoresistive sensors in a full-Wheatstone bridge configuration. An optimized layout of the sensors relative to the neutral mechanical plane leads to both an insensitivity to temperature and an increased sensitivity to pressure, relative to previously reported devices that rely on similar operating principles. Integrating this 3D pressure sensor into a soft, flexible electronics platform yields a system capable of real-time, wireless measurements from the surface of the skin. Placement above the radial and carotid arteries yields high-quality waveforms associated with pulsatile blood flow, with quantitative correlations to blood pressure. The results establish the materials and engineering aspects of a technology with broad potential in remote health monitoring.

Abstract Continued research on the epidermal electronic sensor aims to develop sophisticated platforms that reproduce key multimodal responses in human skin, with the ability to sense various external stimuli, such as pressure, shear, torsion, and touch. The development of such applications utilizes algorithmic interpretations to analyze the complex stimulus shape, magnitude, and various moduli of the epidermis, requiring multiple complex equations for the attached sensor. In this experiment, we integrate silicon piezoresistors with a customized deep learning data process to facilitate in the precise evaluation and assessment of various stimuli without the need for such complexities. With the ability to surpass conventional vanilla deep regression models, the customized regression and classification model is capable of predicting the magnitude of the external force, epidermal hardness and object shape with an average mean absolute percentage error and accuracy of

Flexible electronics offer a multitude of advantages, such as flexibility, lightweight property, portability, and high durability. These unique properties allow for seamless applications to curved and soft surfaces, leading to extensive utilization across a wide range of fields in consumer electronics. These applications, for example, span integrated circuits, solar cells, batteries, wearable devices, bio-implants, soft robotics, and biomimetic applications. Recently, flexible electronic devices have been developed using a variety of materials such as organic, carbon-based, and inorganic semiconducting materials. Silicon (Si) owing to its mature fabrication process, excellent electrical, optical, thermal properties, and cost efficiency, remains a compelling material choice for flexible electronics. Consequently, the research on ultra-thin Si in the context of flexible electronics is studied rigorously nowadays. The thinning of Si is crucially important for flexible electronics as it reduces its bending stiffness and the resultant bending strain, thereby enhancing flexibility while preserving its exceptional properties. This review provides a comprehensive overview of the recent efforts in the fabrication techniques for forming ultra-thin Si using top-down and bottom-up approaches and explores their utilization in flexible electronics and their applications.

Abstract The advantageous role of 2D electron gas presence at the AlGaN/GaN interface attracts huge interest in the field of GaN‐based ultraviolet photodetector technology. However, the presence of high dark current deteriorates the photodetector performance by diminishing several figures of merit. In this work, enhanced figures of merit are demonstrated by employing interdigitated p‐GaN finger structure on the top of the AlGaN/GaN heterostructure. The commonly present high dark current in p‐GaN/AlGaN/GaN planar photodetector is largely reduced (from ≈µA to few pA) by etching the p‐GaN, excluding the electrode region. Furthermore, by using a graphene transparent electrode along with the p‐GaN interdigitated fingers on AlGaN/GaN heterostructure, ultraviolet photodetectors with superior sensitivity (3.55 × 106) and ultrahigh detectivity (1.91 × 1014 cm Hz1/2 W−1) are realized at 360 nm. A comparison of graphene/p‐GaN and Ni/Au/p‐GaN interdigitated fingers and planar p‐GaN (with interdigitated graphene contacts) all on AlGaN/GaN heterostructure allows to understand the dominant roles of electrode transparency and the heterojunction structure. The simple and high electron mobility transistor‐compatible fabrication process of UV detectors provides a unique application in the field of UV sensing technology.

To design a device that is robust to process-induced random variation, this study proposes a machine-learning-based predictive model that can simulate the electrical characteristics of FinFETs with process-induced line-edge roughness. This model, i.e., a Bayesian neural network (BNN) model with horseshoe priors (Horseshoe-BNN), can significantly reduce the simulation time (as compared to the conventional technology computer-aided design (TCAD) simulation method) in a sufficiently accurate manner. Moreover, this model can perform autonomous model selection over the most compact layer size, which is necessary when the amount of data must be limited. The mean absolute percentage error for the mean and standard deviation of the drain-to-source current $\left ({\mathrm {I}_{\mathrm {DS}} }\right)$ were ~0.5% and ~6%, respectively. By estimating the distribution of the current-voltage characteristics, the distributions of the other device metrics, such as off-state leakage current and threshold voltage, can be estimated as well.

Abstract Implantable deep brain stimulation (DBS) systems are utilized for clinical treatment of diseases such as Parkinson’s disease and chronic pain. However, long-term efficacy of DBS is limited, and chronic neuroplastic changes and associated therapeutic mechanisms are not well understood. Fundamental and mechanistic investigation, typically accomplished in small animal models, is difficult because of the need for chronic stimulators that currently require either frequent handling of test subjects to charge battery-powered systems or specialized setups to manage tethers that restrict experimental paradigms and compromise insight. To overcome these challenges, we demonstrate a fully implantable, wireless, battery-free platform that allows for chronic DBS in rodents with the capability to control stimulation parameters digitally in real time. The devices are able to provide stimulation over a wide range of frequencies with biphasic pulses and constant voltage control via low-impedance, surface-engineered platinum electrodes. The devices utilize off-the-shelf components and feature the ability to customize electrodes to enable broad utility and rapid dissemination. Efficacy of the system is demonstrated with a readout of stimulation-evoked neural activity in vivo and chronic stimulation of the medial forebrain bundle in freely moving rats to evoke characteristic head motion for over 36 days.

Uninterrupted monitoring of pressure and temperature at skin interfaces can help to minimize the potential for pressure injuries in hospitalized or bedridden patients. Here, the authors introduce a soft, skin-mountable sensor that can continuously provide readings via antennas mounted under bedding, and demonstrate the functionality and robustness of the devices on patients.

The color filter required for manufacturing a CMOS image sensor was redeveloped to optimize its optical uniformity. An in-depth study of the three-dimensional (3D) coating process and how it gives rise to various radial-shaped striation patterns was conducted. These radial-shaped striation patterns were systematically investigated with reference to two types of patterns: the orthogonal type found only at the orthogonal edges of the wafer and the diagonal type found mostly at the corner of each quadrant. The formation of the orthogonal pattern was based on the wide standing wave created by the incident force of the spreading color photoresist (PR) and the reflective force from the bump pads acting as coating barriers. The diagonal pattern was found to be generated by the turbulent wakes created behind the bump pads by the drag force, which interfered with the coating flow. An in-depth study using Ansys CFX software and an in-line inspection tool revealed that lowering the viscosity of the color PR material is a key factor for improving the phenomenon whereby the 3D striation patterns of the orthogonal and diagonal types are formed. Based on this finding, it was possible to drastically reduce the formation of the 3D striation patterns by decreasing the viscosity of the material comprising each color PR. This study provides not only an empirical and theoretical understanding of the 3D color PR coating mechanism, but also guidelines for future color filter processes.

In this work, we propose a vertical gate-all-around device architecture (GAA-FinFET) with the aim of simultaneously improving device performance as well as addressing the short channel effect (SCE). The GAA-FinFET was built using the technology computer-aided design (TCAD) simulation tool, and then, its electrical characteristics were quantitatively evaluated. The electrical characteristics of the GAA-FinFET were compared to those of conventional FinFET and nano-sheet FET (NSFET) at 7 nm or 5 nm nodes. When comparing the GAA-FinFET against the FinFET, it achieved not only better SCE characteristics, but also higher on-state drive current due to its gate-all-around device structure. This helps to improve the ratio of effective drive current to off-state leakage current (i.e., Ieff/Ioff) by ~30%, resulting in an improvement in DC device performance by ~10%. When comparing the GAA-FinFET against the NSFET, it exhibited SCE characteristics that were comparable or superior thanks to its improved sub-channel leakage suppression. It turned out that the proposed GAA-FinFET (compared to conventional FinFET at the 7 nm or 5 nm nodes, or even beyond) is an attractive option for improving device performance in terms of SCE and series resistance. Furthermore, it is expected that the device structure of GAA-FinFET is very similar to that of conventional FinFET, resulting in further improvement to its electrical characteristics as a result of its gate-all-around device structure without significant modification with respect to the processing steps for conventional FinFET.

Objective and Impact Statement. Real-time monitoring of the temperatures of regional tissue microenvironments can serve as the diagnostic basis for treating various health conditions and diseases. Introduction. Traditional thermal sensors allow measurements at surfaces or at near-surface regions of the skin or of certain body cavities. Evaluations at depth require implanted devices connected to external readout electronics via physical interfaces that lead to risks for infection and movement constraints for the patient. Also, surgical extraction procedures after a period of need can introduce additional risks and costs. Methods. Here, we report a wireless, bioresorbable class of temperature sensor that exploits multilayer photonic cavities, for continuous optical measurements of regional, deep-tissue microenvironments over a timeframe of interest followed by complete clearance via natural body processes. Results. The designs decouple the influence of detection angle from temperature on the reflection spectra, to enable high accuracy in sensing, as supported by in vitro experiments and optical simulations. Studies with devices implanted into subcutaneous tissues of both awake, freely moving and asleep animal models illustrate the applicability of this technology for in vivo measurements. Conclusion. The results demonstrate the use of bioresorbable materials in advanced photonic structures with unique capabilities in tracking of thermal signatures of tissue microenvironments, with potential relevance to human healthcare.

In this paper we demonstrate strain-dependent photoacoustic (PA) characteristics of free-standing nanocomposite transmitters that are made of carbon nanotubes (CNT) and candle soot nanoparticles (CSNP) with an elastomeric polymer matrix. We analyzed and compared PA output performances of these transmitters which are prepared first on glass substrates and then in a delaminated free-standing form for strain-dependent characterization. This confirms that the nanocomposite transmitters with lower concentration of nanoparticles exhibit more flexible and stretchable property in terms of Young’s modulus in a range of 4.08–10.57 kPa. Then, a dynamic endurance test was performed revealing that both types of transmitters are reliable with pressure amplitude variation as low as 8–15% over 100–800 stretching cycles for a strain level of 5–28% with dynamic endurance in range of 0.28–2.8%. Then, after 2000 cycles, the transmitters showed pressure amplitude variation of 6–29% (dynamic endurance range of 0.21–1.03%) at a fixed strain level of 28%. This suggests that the free-standing nanocomposite transmitters can be used as a strain sensor under a variety of environments providing robustness under repeated stretching cycles.

Laser-generated focused ultrasound (LGFU) is an emerging modality for cavitation-based therapy. However, focal pressure amplitudes by LGFU alone to achieve pulsed cavitation are often lacking as a treatment depth increases. This requires a higher pressure from a transmitter surface and more laser energies that even approach to a damage threshold of transmitter. To mitigate the requirement for LGFU-induced cavitation, we propose LGFU configurations with a locally heated focal zone using an additional high-intensity focused ultrasound (HIFU) transmitter. After confirming heat-induced cavitation enhancement using two separate transmitters, we then developed a stacked hybrid optoacoustic-piezoelectric transmitter, which is a unique configuration made by coating an optoacoustic layer directly onto a piezoelectric substrate. This shared curvature design has great practical advantage without requiring the complex alignment of two focal zones. Moreover, this enabled the amplification of cavitation bubble density by 18.5-fold compared to the LGFU operation alone. Finally, the feasibility of tissue fragmentation was confirmed through a tissue-mimicking gel, using the combination of LGFU and HIFU (not via a stacked structure). We expect that the stacked transmitter can be effectively used for stronger and faster tissue fragmentation than the LGFU transmitter alone.

Partial cystectomy procedures for urinary bladder-related dysfunction involve long recovery periods, during which urodynamic studies (UDS) intermittently assess lower urinary tract function. However, UDS are not patient-friendly, they exhibit user-to-user variability, and they amount to snapshots in time, limiting the ability to collect continuous, longitudinal data. These procedures also pose the risk of catheter-associated urinary tract infections, which can progress to ascending pyelonephritis due to prolonged lower tract manipulation in high-risk patients. Here, we introduce a fully bladder-implantable platform that allows for continuous, real-time measurements of changes in mechanical strain associated with bladder filling and emptying via wireless telemetry, including a wireless bioresorbable strain gauge validated in a benchtop partial cystectomy model. We demonstrate that this system can reproducibly measure real-time changes in a rodent model up to 30 d postimplantation with minimal foreign body response. Studies in a nonhuman primate partial cystectomy model demonstrate concordance of pressure measurements up to 8 wk compared with traditional UDS. These results suggest that our system can be used as a suitable alternative to UDS for long-term postoperative bladder recovery monitoring. [ABSTRACT FROM AUTHOR]

Flexible biocompatible electronic systems that leverage key materials and manufacturing techniques associated with the consumer electronics industry have potential for broad applications in biomedicine and biological research. This study reports scalable approaches to technologies of this type, where thin microscale device components integrate onto flexible polymer substrates in interconnected arrays to provide multimodal, high performance operational capabilities as intimately coupled biointerfaces. Specificially, the material options and engineering schemes summarized here serve as foundations for diverse, heterogeneously integrated systems. Scaled examples incorporate >32,000 silicon microdie and inorganic microscale light-emitting diodes derived from wafer sources distributed at variable pitch spacings and fill factors across large areas on polymer films, at full organ-scale dimensions such as human brain, over ~150 cm². In vitro studies and accelerated testing in simulated biofluids, together with theoretical simulations of underlying processes, yield quantitative insights into the key materials aspects. The results suggest an ability of these systems to operate in a biologically safe, stable fashion with projected lifetimes of several decades without leakage currents or reductions in performance. The versatility of these combined concepts suggests applicability to many classes of biointegrated semiconductor devices. [ABSTRACT FROM AUTHOR]

Materials that can serve as long-lived barriers to biofluids are essential to the development of any type of chronic electronic implant. Devices such as cardiac pacemakers and cochlear implants use bulk metal or ceramic packages as hermetic enclosures for the electronics. Emerging classes of flexible, biointegrated electronic systems demand similar levels of isolation from biofluids but with thin, compliant films that can simultaneously serve as biointerfaces for sensing and/or actuation while in contact with the soft, curved, and moving surfaces of target organs. This paper introduces a solution to this materials challenge that combines (i) ultrathin, pristine layers of silicon dioxide (SiO2) thermally grown on device-grade siliconwafers, and (ii) processing schemes that allow integration of these materials onto flexible electronic platforms. Accelerated lifetime tests suggest robust barrier characteristics on timescales that approach 70 y, in layers that are sufficiently thin (less than 1 μm) to avoid significant compromises in mechanical flexibility or in electrical interface fidelity. Detailed studies of temperature- and thickness-dependent electrical and physical properties reveal the key characteristics. Molecular simulations highlight essential aspects of the chemistry that governs interactions between the SiO2 and surrounding water. Examples of use with passive and active components in high-performance flexible electronic devices suggest broad utility in advanced chronic implants. [ABSTRACT FROM AUTHOR]

Developing advanced surgical tools for minimally invasive procedures represents an activity of central importance to improving human health. A key challenge is in establishing biocompatible interfaces between the classes of semiconductor device and sensor technologies that might be most useful in this context and the soft, curvilinear surfaces of the body. This paper describes a solution based on materials that integrate directly with the thin elastic membranes of otherwise conventional balloon catheters, to provide diverse, multimodal functionality suitable for clinical use. As examples, we present sensors for measuring temperature, flow, tactile, optical and electrophysiological data, together with radiofrequency electrodes for controlled, local ablation of tissue. Use of such 'instrumented' balloon catheters in live animal models illustrates their operation, as well as their specific utility in cardiac ablation therapy. The same concepts can be applied to other substrates of interest, such as surgical gloves. [ABSTRACT FROM AUTHOR]

This letter describes the physics and application of an approach to transfer printing that uses stamps with microstructures of relief embossed into their surfaces. Experimental measurement of velocity-dependent adhesive strength as a function of relief geometry reveals key scaling properties and provides a means for comparison to theoretical expectation. Formation of transistor devices that use nanoribbons of silicon transfer printed directly onto glass substrates without adhesive layers demonstrates the use of this type of approach for a high-performance (mobilities >325 cm2/V s and on/off ratios >105) single crystal silicon on glass technology. [ABSTRACT FROM AUTHOR]

The article focuses on the development of a biodegradable microneedle sensor array for continuous glucose monitoring (CGM) in patients with diabetes. It mentions the sensor array, which is painless, wireless, and minimally invasive, continuously monitors glucose levels in the interstitial fluid with high sensitivity and offers a tether-free CGM system using a smartphone application.

The article presents a study on microfabricated three-dimensional frameworks that are complaint, multifunctional neural interfaces to assembloids and spheroids. It discusses the electrochemical deposition of platinum black and measurements of impedance, the formation of three-dimensional cortical neuron/astrocyte cocultures derived from human induced pluripotent stem cells, and the preparation of spheroids for optogenetic analysis.

The article discusses a study which described a flexible, wireless monitoring sensor for tracking temperature and pressure at the interface between the skin and the therapeutic compression garments. Technical foundations and measurement capabilities are supported by detailed studies of the materials and engineering aspects of the devices along with clinical pilot trials on patients with different pathologies. Results of the study are discussed. Materials and methods are described.

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. [ABSTRACT FROM AUTHOR]

We report classes of electronic systems that achieve thicknesses, effective elastic moduli, bending stiffnesses, and areal mass densities matched to the epidermis. Unlike traditional wafer-based technologies, laminating such devices onto the skin leads to conformal contact and adequate adhesion based on van der Waals interactions alone, in a manner that is mechanically invisible to the user. We describe systems incorporating electrophysiological, temperature, and strain sensors, as well as transistors, light-emitting diodes, photodetectors, radio frequency inductors, capacitors, oscillators, and rectifying diodes. Solar cells and wireless coils provide options for power supply. We used this type of technology to measure electrical activity produced by the heart, brain, and skeletal muscles and show that the resulting data contain sufficient information for an unusual type of computer game controller. [ABSTRACT FROM AUTHOR]