In a multiple-receiver wireless power transfer (WPT) system, determining the condition for uniform power distribution at a high transfer efficiency is a challenging issue. In this paper, a selective ...WPT technique using magnetic resonance coupling (MRC) is introduced for smart power delivery in a multiple-receiver system. The proposed method selectively and exclusively delivers power to only one designated receiver among multiple receivers, eliminating the cross-coupling effect and unbalanced power division problem across the receivers. This is achieved by separating the resonant frequencies of the receivers to isolate the coupling effects between coils. The power division ratio of the receivers is controlled by changing the duration time ratio for power transfer. In this paper, a one-transmitter three-receiver selective MRC system is designed and fabricated. The power distribution is demonstrated under impedance matched condition, showing a power transfer efficiency of 24%-29% at a very small coupling coefficient of 0.01 with a 12-mm-diameter receiver coil. Distance compensation and a one-way communication of time division multiple access are demonstrated for a multiple-receiver system, using the proposed method.
Abstract Several variations of microelectrode arrays are used to record and stimulate intracortical neuronal activity. Bypassing the immune response to maintain a stable recording interface remains a ...challenge. Companies and researchers are continuously altering the material compositions and geometries of the arrays in order to discover a combination that allows for a chronic and stable electrode–tissue interface. From this interface, they wish to obtain consistent quality recordings and a stable, low impedance pathway for charge injection over extended periods of time. Despite numerous efforts, no microelectrode array design has managed to evade the host immune response and remain fully functional. This study is an initial effort comparing several microelectrode arrays with fundamentally different configurations for use in an implantable epilepsy prosthesis. Specifically, NeuroNexus (Michigan) probes, Cyberkinetics (Utah) Silicon and Iridium Oxide arrays, ceramic-based thin-film microelectrode arrays (Drexel), and Tucker-Davis Technologies (TDT) microwire arrays are evaluated over a 31-day period in an animal model. Microelectrodes are compared in implanted rats through impedance, charge capacity, signal-to-noise ratio, recording stability, and elicited immune response. Results suggest significant variability within and between microelectrode types with no clear superior array. Some applications for the microelectrode arrays are suggested based on data collected throughout the longitudinal study. Additionally, specific limitations of assaying biological phenomena and comparing fundamentally different microelectrode arrays in a highly variable system are discussed with suggestions on how to improve the reliability of observed results and steps needed to develop a more standardized microelectrode design.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Vagus nerve stimulation (VNS) has been on the forefront of inflammatory disorder research and has yielded many promising results. Questions remain, however, about the biological mechanisms of such ...treatments and the inconsistencies in the methods used in research efforts. Here, we aimed to clarify the inflammatory response to intraperitoneal (IP) injections of lipopolysaccharide (LPS) in rats, while analyzing corresponding effects of electrical stimulation to subdiaphragmatic branches (anterior gastric, accessory celiac, and hepatic) of the left vagus nerve. We accomplished an in-depth characterization of the time-varying cytokine cascade response in the serum of 58 rats to an acute IP LPS challenge over a 330-minute period by utilizing curve-fitting and starting point-alignment methods. We then explored the post-LPS neuromodulation effects of electrically stimulating individually cuffed subdiaphragmatic branches. Through our analysis, we found there to be a consistent order of IP LPS cytokine response (IL-10, TNF-α, GM-CSF, IL-17F, IL-6, IL-22, INF-γ). Apart from IL-10, the IP cytokine cascade was more variable in starting time and occurred later than in previously recorded intravenous (IV) challenges. We also found distinct regulatory effects on multiple cytokine levels by each of the three subdiaphragmatic stimulation subsets. While the time-variability of IP LPS use in rats complicates its utility, we have shown it to be a practical, arguably more physiologically relevant method than IV in rats when our methods are used. More importantly, we have shown that selective subdiaphragmatic neurostimulation can be utilized to selectively induce specific effects on inflammation in the body.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A novel integrated 3D micro‐supercapacitor is reported. A through‐via bottom electrode technique is utilized for the first time for supercapacitor fabrication, and a highly miniaturized, flexible, ...and all‐solid‐state micro‐supercapacitor with 3D integration capability is achieved. Module‐wise compact integration of supercapacitors and their versatile powering applications are demonstrated. This device enables high‐power energy storage in small‐scale electronics.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
5.
Miniaturizing wireless implants Mei, Henry; Irazoqui, Pedro P
Nature biotechnology,
10/2014, Volume:
32, Issue:
10
Journal Article
Peer reviewed
Since the first pacemaker was implanted over 50 years ago, implantable medical devices have undergone rapid development, resulting in smaller, more capable and less invasive systems for patients. Yet ...technologies to power these devices, such as wireless power transfer from an external source, have lagged behind. In The Proceedings of the National Academy of Sciences, Ho et al.2 now present an approach to wirelessly transfer sufficient power to operate a pacemaker the size of a grain of rice implanted deep in the chest cavity of a rabbit. This major advance hinges on a novel wireless electromagnetic energy transmitter that can be placed on the skin or perhaps integrated in clothing. The transmitter overcomes the interference of biological tissues to effectively focus electromagnetic energy through the body. The findings have clear clinical implications for the development of small devices implanted deep in the bodyfor example, in blood vessels.
We report novel three-dimensional (3D) microcavity array electrodes for high-capacitance all-solid-state microsupercapactiors. The microcavity arrays are formed in a polymer substrate via a ...plasma-assisted reactive ion etching (RIE) process and provide extra sidewall surface areas on which the active materials are grown in the form of nanofibers. This 3D structure leads to an increase in the areal capacitance by a factor of 2.56 for a 15-μm-deep cavity etching, agreeing well with the prediction. The fabricated microsupercapactiors exhibit a maximum areal capacitance of 65.1 mF cm–2 (a volumetric capacitance of 93.0 F cm–3) and an energy density of 0.011 mWh cm–2 (a volumetric energy density of 16.4 mWh cm–3) which substantially surpass previously reported values for all-solid-state flexible microsupercapacitors. The devices show good electrochemical stability under extended voltammetry cycles and bending cycles. It is demonstrated that they can sustain a radio frequency (rf) microsystem in a temporary absence of a power supply. These results suggest the potential utility of our 3D microsupercapactiors as miniaturized power sources in wearable and implantable medical devices.
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IJS, KILJ, NUK, PNG, UL, UM
The charge storage characteristics of a composite nanoarchitecture with a highly functional 3D morphology are reported. The electrodes are formed by the electropolymerization of aniline monomers into ...a nanometer‐thick polyaniline (PANI) film that conformally coats graphitic petals (GPs) grown by microwave plasma chemical vapor deposition (MPCVD) on conductive carbon cloth (CC). The hybrid CC/GPs/PANI electrodes yield results near the theoretical maximum capacitance for PANI of 2000 F g−1 (based on PANI mass) and a large area‐normalized specific capacitance of ≈2.6 F cm−2 (equivalent to a volumetric capacitance of ≈230 F cm−3) at a low current density of 1 A g−1 (based on PANI mass). The specific capacitances remain above 1200 F g−1 (based on PANI mass) for currents up to 100 A g−1 with correspondingly high area‐normalized values. The hybrid electrodes also exhibit a high rate capability with an energy density of 110 Wh kg−1 and a maximum power density of 265 kW kg−1 at a current density of 100 A g−1. Long‐term cyclic stability is good (≈7% loss of initial capacitance after 2000 cycles), with coulombic efficiencies >99%. Moreover, prototype all‐solid‐state flexible supercapacitors fabricated from these hybrid electrodes exhibit excellent energy storage performance.
Thin graphitic petals grown from carbon cloth form the basis of a flexible, solid‐state supercapacitor that employs polyaniline coating as the pseudocapacitive material. This structure exhibits very high area‐, volume‐, and mass‐based specific capacitances and energy/power densities. The cyclic stability and Coulombic efficiencies are good, and functional devices exhibit virtually no performance degradation under highly strained bent and twisted conditions.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Transfer printing of thin-film nanoelectronics from their fabrication wafer commonly requires chemical etching on the sacrifice of wafer but is also limited by defects with a low yield. Here, we ...introduce a wafer-recyclable, environment-friendly transfer printing process that enables the wafer-scale separation of high-performance thin-film nanoelectronics from their fabrication wafer in a defect-free manner that enables multiple reuses of the wafer. The interfacial delamination is enabled through a controllable cracking phenomenon in a water environment at room temperature. The physically liberated thin-film nanoelectronics can be then pasted onto arbitrary places of interest, thereby endowing the particular surface with desirable add-on electronic features. Systematic experimental, theoretical, and computational studies reveal the underlying mechanics mechanism and guide manufacturability for the transfer printing process in terms of scalability, controllability, and reproducibility.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
After an amputation, advanced prosthetic limbs can be used to interface with the nervous system and restore motor function. Despite numerous breakthroughs in the field, many of the recent research ...advancements have not been widely integrated into clinical practice. This review highlights recent innovations in neuromuscular implants—specifically those that interface with skeletal muscle—which could improve the clinical translation of prosthetic technologies. Skeletal muscle provides a physiologic gateway to harness and amplify signals from the nervous system. Recent surgical advancements in muscle reinnervation surgeries leverage the “bio‐amplification” capabilities of muscle, enabling more intuitive control over a greater number of degrees of freedom in prosthetic limbs than previously achieved. We anticipate that state‐of‐the‐art implantable neuromuscular interfaces that integrate well with skeletal muscle and novel surgical interventions will provide a long‐term solution for controlling advanced prostheses. Flexible electrodes are expected to play a crucial role in reducing foreign body responses and improving the longevity of the interface. Additionally, innovations in device miniaturization and ongoing exploration of shape memory polymers could simplify surgical procedures for implanting such interfaces. Once implanted, wireless strategies for powering and transferring data from the interface can eliminate bulky external wires, reduce infection risk, and enhance day‐to‐day usability. By outlining the current limitations of neuromuscular interfaces along with potential future directions, this review aims to guide continued research efforts and future collaborations between engineers and specialists in the field of neuromuscular and musculoskeletal medicine.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The ultimate goal of epilepsy therapies is to provide seizure control for all patients while eliminating side effects. Improved specificity of intervention through on-demand approaches may overcome ...many of the limitations of current intervention strategies. This article reviews the progress in seizure prediction and detection, potential new therapies to provide improved specificity, and devices to achieve these ends. Specifically, we discuss (1) potential signal modalities and algorithms for seizure detection and prediction, (2) closed-loop intervention approaches, and (3) hardware for implementing these algorithms and interventions. Seizure prediction and therapies maximize efficacy, whereas minimizing side effects through improved specificity may represent the future of epilepsy treatments.
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