Nociceptive Memristor Kim, Yumin; Kwon, Young Jae; Kwon, Dae Eun ...
Advanced materials (Weinheim),
February 22, 2018, Letnik:
30, Številka:
8
Journal Article
Recenzirano
The biomimetic characteristics of the memristor as an electronic synapse and neuron have inspired the advent of new information technology in the neuromorphic computing. The application of the ...memristors can be extended to the artificial nerves on condition of the presence of electronic receptors which can transfer the external stimuli to the internal nerve system. In this work, nociceptor behaviors are demonstrated from the Pt/HfO2/TiN memristor for the electronic receptors. The device shows four specific nociceptive behaviors; threshold, relaxation, allodynia, and hyperalgesia, according to the strength, duration, and repetition rate of the external stimuli. Such nociceptive behaviors are attributed to the electron trapping/detrapping to/from the traps in the HfO2 layer, where the depth of trap energy level is ≈0.7 eV. Also, the built‐in potential by the work function mismatch between the Pt and TiN electrodes induces time‐dependent relaxation of trapped electrons, providing the appropriate relaxation behavior. The relaxation time can take from several milliseconds to tens of seconds, which corresponds to the time span of the decay of biosignal. The material‐wise evaluation of the electronic nociceptor in comparison with other material, which did not show the desired functionality, Pt/Ti/HfO2/TiN, reveals the importance of careful material design and fabrication.
Nociceptor behaviors are demonstrated from a Pt/HfO2/TiN memristor as an electrical nociceptor. The memristor shows the characteristics of allodynia, and hyperalgesia, which are typical behaviors of biological nociceptors. Such nociceptive responses are attributed to the threshold switching and resistance switching of the memristor, which are caused by electron trapping/detrapping to/from the traps in the HfO2 layer.
Intrinsically stretchable organic solar cells (IS‐OSCs), consisting of all stretchable layers, are attracting significant attention as a future power source for wearable electronics. However, most of ...the efficient active layers for OSCs are mechanically brittle due to their rigid molecular structures designed for high electrical and optical properties. Here, a series of new polymer donors (PDs, PhAmX) featuring phenyl amide (N1,N3‐bis((5‐bromothiophen‐2‐yl)methyl)isophthalamide, PhAm)‐based flexible spacer (FS) inducing hydrogen‐bonding (H‐bonding) interactions is developed. These PDs enable IS‐OSCs with a high power conversion efficiency (PCE) of 12.73% and excellent stretchability (PCE retention of >80% of the initial value at 32% strain), representing the best performances among the reported IS‐OSCs to date. The incorporation of PhAm‐based FS enhances the molecular ordering of PDs as well as their interactions with a Y7 acceptor, enhancing the mechanical stretchability and electrical properties simultaneously. It is also found that in rigid OSCs, the PhAm5:Y7 blend achieves a much higher PCE of 17.5% compared to that of the reference PM6:Y7 blend. The impact of the PhAm‐FS linker on the mechanical and photovoltaic properties of OSCs is thoroughly investigated.
Efficient, intrinsically stretchable organic solar cells (IS‐OSCs) are developed by designing a new series of polymer donors (PDs, PhAm) featuring hydrogen‐bonding‐capable flexible spacers. High power conversion efficiency (PCE = 12.7%) and stretchability (PCE retention of > 80% at 32% strain) are demonstrated, which represent the best performances in terms of both PCE and stretchability among the IS‐OSCs reported to date.
Abstract
Hematite has a great potential as a photoanode for photoelectrochemical (PEC) water splitting by converting solar energy into hydrogen fuels, but the solar-to-hydrogen conversion efficiency ...of state-of-the-art hematite photoelectrodes are still far below the values required for practical hydrogen production. Here, we report a core-shell formation of gradient tantalum-doped hematite homojunction nanorods by combination of hydrothermal regrowth strategy and hybrid microwave annealing, which enhances the photocurrent density and reduces the turn-on voltage simultaneously. The unusual bi-functional effects originate from the passivation of the surface states and intrinsic built-in electric field by the homojunction formation. The additional driving force provided by the field can effectively suppress charge–carrier recombination both in the bulk and on the surface of hematite, especially at lower potentials. Moreover, the synthesized homojunction shows a remarkable synergy with NiFe(OH)
x
cocatalyst with significant additional improvements of photocurrent density and cathodic shift of turn-on voltage. The work has nicely demonstrated multiple collaborative strategies of gradient doping, homojunction formation, and cocatalyst modification, and the concept could shed light on designing and constructing the efficient nanostructures of semiconductor photoelectrodes in the field of solar energy conversion.
Vacuum tubes that sparked the electronics era had given way to semiconductor transistors. Despite their faster operation and better immunity to noise and radiation compared to the transistors, the ...vacuum device technology became extinct due to the high power consumption, integration difficulties, and short lifetime of the vacuum tubes. We combine the best of vacuum tubes and modern silicon nanofabrication technology here. The surround gate nanoscale vacuum channel transistor consists of sharp source and drain electrodes separated by sub-50 nm vacuum channel with a source to gate distance of 10 nm. This transistor performs at a low voltage (<5 V) and provides a high drive current (>3 microamperes). The nanoscale vacuum channel transistor can be a possible alternative to semiconductor transistors beyond Moore’s law.
This paper designs a simple model reference adaptive control based speed controller (MRAC-SC) for a surface-mounted permanent magnet synchronous motor drive. The proposed adaptive scheme is designed ...to track a reference model that ensures the desired exponential decay of a controlled speed error trajectory. Also, the proposed MRAC method includes an adaptive compensating control term and a stabilizing feedback control term. The former is proposed to compensate for uncertain model parameters (i.e., inertia, friction, and load torque) and the latter is constructed to asymptotically stabilize the error dynamics. The asymptotic stability of the closed loop is guaranteed with both control terms using the Lyapunov approach. The comparative studies between the proposed MRAC-SC, the nonadaptive model reference speed controller, and the conventional proportional-integral SC are performed to justify a fast transient response, a good tracking possibility, and robustness against the parameter uncertainties of the proposed MRAC technique.
Cardiovascular disease (CVD) is a health problem worldwide, and elevated cholesterol levels are a key risk factor for the disease. Dysbiotic gut microbiota has been shown to be associated with CVD ...development. However, the beneficial effects of healthy microbiota in decreasing cholesterol levels have not been summarized. Herein, we begin by discussing the potential mechanisms by which the gut microbiota reduces cholesterol levels. We further sketch the application of probiotics from the genera Lactobacillus and Bifidobacterium in reducing cholesterol levels in clinical studies. Finally, we present the cholesterol-lowering function of beneficial commensal microbes, such as Akkermansia and Bacteroides spp., as these microbes have potential to be the next-generation probiotics (NGPs). The information reviewed in this paper will help people to understand how the gut microbiome might alter cholesterol metabolism and enable the development of NGPs to prevent and treat CVD.
Short-chain fatty acids and secondary bile acids can decrease cholesterol levels by regulating cholesterol metabolism.Microbial bile salt hydrolases can increase cholesterol disposal rates by accelerating its conversion to bile acids.Uncultured bacteria from the human gut can transform cholesterol to coprostanol.Probiotics from the genera Lactobacillus and Bifidobacterium are efficient reducers of cholesterol levels in clinical studies.Several candidate next-generation probiotics, including Akkermansia muciniphila, Bacteroides spp., Clostridium spp., Christensenella minuta, Eubacterium spp., and Faecalibacterium prausnitzii, have been shown to decrease cholesterol levels in human or animal studies.
A humidity sensor on cellulose paper is demonstrated using single-walled carbon nanotubes functionalized with carboxylic acid. The conductance shift of the nanotube network entangled on the ...microfibril cellulose is utilized for the humidity sensing. Compared to the control sensor made on a glass substrate, the cellulose-mediated charge transport on the paper substrate enhances the sensitivity. The sensor response exhibits linear behavior up to a relative humidity of 75% with good repeatability and low hysteresis. A simple circuit model is used to explain the sensor results. This approach is a step toward future paper electronics for low-cost disposable applications.
This paper proposes an online parameter estimation method based on a discrete-time dynamic model for the interior permanent-magnet synchronous motors (IPMSMs). The proposed estimation technique, ...which takes advantage of the difference in dynamics of motor parameters, consists of two affine projection algorithms. The first one is designed to accurately estimate the stator inductances, whereas the second one is designed to precisely estimate the stator resistance, rotor flux linkage, and load torque. In this paper, the adaptive decoupling proportional-integral (PI) controllers with the maximum torque per ampere operation, which utilize the previously identified parameters in real time, are chosen to verify the effectiveness of the proposed parameter estimation scheme. The simulation results via MATLAB/Simulink and the experimental results via a prototype IPMSM drive system with a TI TMS320F28335 DSP are presented under various conditions. A comparative study with the conventional decoupling PI control method is carried out to demonstrate the better performances (i.e., faster dynamic response, less steady-state error, more robustness, etc.) of the adaptive decoupling PI control scheme based on the proposed online parameter estimation technique.
This paper designs a predictive speed controller of interior permanent-magnet synchronous motor (IPMSM) based on finite control set (FCS)-model predictive control (MPC). The proposed predictive speed ...controller has a cascade-free structure that comprises a single predictive control function for the speed and dq-axis stator currents. The future rotor speed and stator currents are predicted at each sampling interval. Then, the proposed predictive control function is evaluated to determine the optimal switching states for the IPMSM drive. In high-performance speed-controlled drive, the unknown load torque disturbance has to be suppressed. Therefore, the load torque disturbance estimator using the two-stage extended Kalman filter (TSEKF) is proposed to enhance the dynamic performance of the IPMSM drive. The proposed TSEKF simultaneously estimates the system states, which greatly improve the model prediction process. The proposed predictive speed control is simple and compact, which demonstrates a faster transient response and a robust feature to mechanical system parameter variations when compared with the conventional cascaded speed control under a wide speed range and load torque variations. The experimental results on a prototype IPMSM drive built on a Texas Instruments TMS320F28335 floating point digital signal processing (DSP) board are presented considering the constant torque and flux-weakening regions to confirm the feasibility of the proposed FCS-MPC scheme.
In patients with idiopathic pulmonary fibrosis (IPF), the effects of antifibrotic agents on the prognosis remain unclear. This study aimed to investigate the impact of antifibrotic treatment on the ...risks of mortality, hospitalisation, and acute exacerbation in real-world patients with IPF. A total of 1213 IPF patients (biopsy-proven cases: 405) were included in this retrospective study. Propensity score matching was used to adjust for differences in baseline characteristics between patients who received antifibrotic treatment and who did not. A Cox proportional hazard model was used to compare the risks of all-cause mortality, hospitalisation, acute exacerbation, and mortality following acute exacerbation between the two groups. From the 1213 patients, 474 matched pairs were generated. The mean age of the patients in the matched cohort was 65.8 years and 82.8% were men. The median follow-up duration was 27 months. Antifibrotic treatment significantly reduced the risks of mortality hazard ratio (HR), 0.59; 95% confidence interval (CI), 0.48-0.72; p < 0.001, all-cause hospitalisation (HR 0.71), respiratory-related hospitalisation (HR 0.67), acute exacerbation (HR 0.69), and mortality after acute exacerbation (HR 0.60). Our results suggest that antifibrotic treatment may reduce the risks of all-cause mortality, hospitalisation, acute exacerbation, and mortality after acute exacerbation in patients with IPF.
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