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In this paper, we introduce an ultra-sensitive optical sensing platform based on the parity-time-reciprocal scaling (PTX)-symmetric non-Hermitian metasurfaces, which leverage exotic singularities, such as the exceptional point (EP) and the coherent perfect absorber-laser (CPAL) point, to significantly enhance the sensitivity and detectability of photonic sensors. We theoretically studied scattering properties and physical limitations of the PTX-symmetric metasurface sensing systems with an asymmetric, unbalanced gain-loss profile. The PTX-symmetric metasurfaces can exhibit similar scattering properties as their PT-symmetric counterparts at singular points, while achieving a higher sensitivity and a larger modulation depth, possible with the reciprocal-scaling factor (i.e., X transformation). Specifically, with the optimal reciprocal-scaling factor or near-zero phase offset, the proposed PTX-symmetric metasurface sensors operating around the EP or CPAL point may achieve an over 100 dB modulation depth, thus paving a promising route toward the detection of small-scale perturbations caused by, for example, molecular, gaseous, and biochemical surface adsorbates. [Image: see text]

We herein introduce a non-Hermitian parity-time (PT)-symmetric telemetry platform, capable of wirelessly and robustly acquiring information of passive sensors and chemiresistive or piezoresistive transducers. We theoretically and experimentally demonstrate that the PT-symmetric radio frequency (RF) system, which consists of an active reader and a passive sensor to obey parity (space inversion) and time-reversal symmetries, may provide not only an improved sensitivity but also rapid, accurate, and robust acquisition of sensor data. The unidirectional reflectionless properties arising from the spontaneous PT symmetry-breaking may result in high- $Q$ resonances and thus high resolvability in the measured reflection spectrum. Furthermore, the sensor’s effective resistance (capacitance) can be wirelessly queried by electronically tuning the negative impedance converter (varactors) on the active reader, which allows observation of dual-band reflectionless phenomena. Unlike traditional telemetry systems, the measurement results are robust to the variations in the inductive coupling strength, namely, the distance and alignment between the two coil antennas. The proposed PT-symmetric telemetry paradigm may have an impact on a wide range of wireless sensing and instrumentation applications.

The requirement of multilevel cell (MLC) resistive random access memory (RRAM) for computing is different than that for MLC storage. It generally requires a linearly spaced conductance median and an ultratight conductance distribution, as the column current are summed up for analog computation. In this article, 3-bit per cell RRAM that is suitable for accurate inference of a deep neural network (DNN) is demonstrated, with ultratight conductance distribution ( $5.3 \times $ and $4.4 \times $ , respectively, compared to the 3-bit per cell RRAM used as MLC storage.

We herein introduce a lightweight and zero-power smart face mask, capable of wirelessly monitoring coughs in real time and identifying proper mask wearing in public places during a pandemic. The smart face mask relies on the compact, battery-free radio frequency (RF) harmonic transponder, which is attached to the inner layer of the mask for detecting its separation from the face. Specifically, the RF transponder composed of miniature antennas and passive frequency multiplier is made of spray-printed silver nanowires (AgNWs) coated with a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) passivation layer and the recently discovered multiscale porous polystyrene-iblock/i-poly(ethylene-iran/i-butylene)-iblock/i-polystyrene (SEBS) substrate. Unlike conventional on-chip or on-board wireless sensors, the SEBS-AgNWs/PEDOT:PSS-based RF transponder is lightweight, stretchable, breathable, and comfortable. In addition, this wireless device has excellent resilience and robustness in long-term and repeated usages (i.e., repeated placement and removal of the soft transponder on the mask). We foresee that this wireless smart face mask, providing simultaneous cough and mask-wearing monitoring, may mitigate virus-transmissive events by tracking the potential contagious person and identifying mask-wearing conditions. Moreover, the ability to wirelessly assess cough frequencies may improve diagnosis accuracy for dealing with several diseases, such as chronic obstructive pulmonary disease.

The rapid advent of radio-frequency (RF) and microwave technologies and systems have given rise to serious electromagnetic pollution, interference and jamming for high-precision detection devices, and even threats to human health. To mitigate these negative impacts, electromagnetic interference (EMI) shielding materials and structures have been widely deployed to isolate sophisticated instruments or human settlements from potential EMI sources growing every day. We discuss recent advances in lightweight, low-profile electromagnetic absorbing media, such as metamaterials, metasurfaces, and nanomaterial-based solutions, which may provide a relatively easy solution for EMI shielding and suppressing unwanted RF and microwave noises. We present a general review of the recent progress on theories, designs, modeling techniques, fabrication, and performance comparison for these emerging EMI and electromagnetic compatibility (EMC) media.

Achieving extraordinarily high sensitivity is a long-sought goal in the development of novel and more capable electromagnetic sensors. We present here how a coherent perfect absorber-laser (CPAL) e...

In this paper, we propose and demonstrate the multi-band wireless power transfer (WPT) systems based on quantum-inspired symmetries. A non-Hermitian quantum system satisfying the parity-time $(PT)$-symmetry (space-time reflection symmetry) can have multiple real eigenfrequencies that depend on the coupling strength and non-Hermiticity index. By analogy, the PT-symmetric WPT system can provide multimodal or even wideband operations with high transmission efficiencies through adjustment of the effective quality-factor of resonantly coupled oscillators (analogous to non-Hermiticity) and their mutual inductive/capacitive coupling. We present here basic theory and experimental validations for achieving dual-band and (b) tri-band PT-symmetric WPT systems with engineerable operating frequencies.

Objective This study aimed to construct a biosensor using Au nanoparticles (Au NPs) and reduced graphene-polyamide-amine-ferrocene (rGO-PAMAM-Fc) nanomaterials designed for rapid and sensitive detection of cholesterol. Materials and methods In this study, a highly sensitive biosensor based on Au NPs/ rGO-PAMAM-Fc nanomaterials was manufactured for detection of cholesterol. The rGO-PAMAM-Fc and Au NPs were modified on the surface of the electrode and then coated with cholesterol oxidase (ChOx) and cholesterol esterase (ChEt) to develop the ChOx&ChEt/Au NPs/rGO-PAMAM-Fc biosensor. Results The capability of rGO-PAMAM-Fc nanomaterials in fabricating a more efficient biosensor was validated through stability, selectivity and reproducibility checks. Under optimal conditions, the newly developed biosensor showed a linear relationship with logarithm of cholesterol concentration from 0.0004 to 15.36 mM (R 2=0.9986), and a low detection limit of 2 nM was obtained at the signal/noise ratio of 3. Conclusion The ChOx&ChEt/Au NPs/rGO-PAMAM-Fc biosensor was successfully applied for the measurement of cholesterol in human serum, which implies that the biosensor has a potential application in clinical diagnostics.

Neuromorphic computing systems built with resistive random access memory (RRAM) are attractive solutions for implementing deep learning on-chip. In this paper, the single event and cumulative radiation damage susceptibility of a 1-transistor-1-resistor synaptic array architecture is investigated for the inference stage of a neuromorphic system. A physics-based SPICE RRAM model is developed to simulate the analog switching behavior of HfO x -based RRAM devices. SPICE simulations using the RRAM model are performed to capture the effects of transient heavy-ion strikes and experimental results obtained on GeSe-based RRAM devices are used to model the effects of cumulative radiation dose. Error patterns are fed into the software simulation of a multilayer perceptron, a representative artificial neural network for MNIST handwritten digit recognition. Radiation effects on the inference accuracy are analyzed. The results of the analysis indicate that the RRAM-based neuromorphic computing system is highly resistant to transient single-event effects due to the low cross section. The system is also shown to be tolerant to multi-Mrad levels of total ionizing and displacement damage dose.

We introduce cascaded parity-time (PT)-symmetric artificial sheets (e.g. metasurfaces or frequency selective surfaces) that may exhibit multiple higher-order laser-absorber modes and bidirectional reflectionless transmission resonances within the PT-broken phase, as well as a unidirectional reflectionless transmission resonance associated with the exceptional point (EP). We derive the explicit expressions of the gain–loss parameter required for obtaining these modes and their intriguing physical properties. By exploiting the cascaded PT structures, the gain–loss threshold for the self-dual laser-absorber operation can be remarkably lowered, while the EP remains unaltered. We further study interferometric sensing based on such a multimodal laser-absorber and demonstrate that its sensitivity may be exceptionally high and proportional to the number of metasurfaces along the light propagation direction.

In this work, single event effects (SEEs) are analyzed in SRAM- and RRAM-based neuromorphic computing systems. SPICE simulation is employed to model single event upset (SEU) at the array level. Then SEU effects are mapped to the weight pattern change of a multi-layer perceptron (MLP), a representative artificial neural network for MNIST handwritten digit recognition. Simulations show that the RRAM-based MLP has less susceptibility to SEEs compared with the SRAM architecture. Improvements to the SRAM-based MLP reliability may be achieved by lowering bit-width and enlarging network size.

Jianmeng Zhu,1 Zhilu Ye,1 Xiaoying Fan,1 Hongqin Wang,1 Zhen Wang,1,2 Bingyu Chen1,2 1Department of Clinical Laboratory, Chun’an First People’s Hospital (Zhejiang Provincial People’s Hospital Chun’an Branch), Hangzhou, Zhejiang, China; 2Department of Blood Transfusion, Zhejiang Provincial People’s Hospital, People’s Hospital of Hangzhou Medical College, Hangzhou, Zhejiang, China Objective: This study aimed to construct a biosensor using Au nanoparticles (Au NPs) and reduced graphene-polyamide-amine-ferrocene (rGO-PAMAM-Fc) nanomaterials designed for rapid and sensitive detection of cholesterol.Materials and methods: In this study, a highly sensitive biosensor based on Au NPs/rGO-PAMAM-Fc nanomaterials was manufactured for detection of cholesterol. The rGO-PAMAM-Fc and Au NPs were modified on the surface of the electrode and then coated with cholesterol oxidase (ChOx) and cholesterol esterase (ChEt) to develop the ChOx&ChEt/Au NPs/rGO-PAMAM-Fc biosensor.Results: The capability of rGO-PAMAM-Fc nanomaterials in fabricating a more efficient biosensor was validated through stability, selectivity and reproducibility checks. Under optimal conditions, the newly developed biosensor showed a linear relationship with logarithm of cholesterol concentration from 0.0004 to 15.36 mM (R2=0.9986), and a low detection limit of 2 nM was obtained at the signal/noise ratio of 3.Conclusion: The ChOx&ChEt/Au NPs/rGO-PAMAM-Fc biosensor was successfully applied for the measurement of cholesterol in human serum, which implies that the biosensor has a potential application in clinical diagnostics. Keywords: diagnostics, graphene, polyamide-amine, ferrocene, Au nanoparticles

Resonance is a ubiquitous phenomenon observed in a wide range of physical systems. Recently, with the Fano resonance exerting remarkable potential for optical, acoustic, atomic, and electronic applications, it is vital to control and even dynamically reconfigure the resonance line shape and bandwidth, in addition to its frequency. In this work, we introduce a parity-time-reciprocal scaling ( PTX)-symmetric structure, which can offer a promising avenue for tailoring the resonance frequency and line shape of electronic circuits. We have theoretically studied the resonance behavior of such a PTX-symmetric electronic system, particularly for dependencies of resonant peaks and line-shapes on the non-Hermiticity, coupling coefficient, and the scaling coefficient introduced by the reciprocal scaling ( X) transformation. Our results demonstrate that, at resonance frequencies, a transition between Fano and Lorentzian line-shapes is possible with a specific reciprocal scaling rule applied to lumped-element circuits.