Chunlei Wang

Bipolar electrochemistry drives graphite exfoliation, transport of graphene-related species, and electrodeposition simultaneously in one reactor through a wirelessly polarized graphite electrode. Because these processes are coupled within the same electrolyte, the local ion concentrations, graphene-related species concentration, and current density that control the deposition are difficult to measure experimentally. A three-dimensional multiphysics model coupling charge, species, momentum, and energy conservation was developed, in which DFT calculations on simplified static reference systems provided the effective intercalation numbers of the OH- and H3O+ assisted exfoliation pathways (x = 4 and y = 3) for the COMSOL-based continuum simulations. The model simulated graphite consumption and feeding electrode deposition under different operating temperatures, graphite rod arrangements, and reactor geometries. Raising the temperature from 25 to 80 °C increased the simulated 24 h current density by approximately 82%. Adding a second pair of graphite rods increased the current density by approximately 16%, almost independently of the pair spacing, whereas the deposition was maximized when the spacing equaled the feeding electrode width (s/l = 1). Increasing the rectangular reactor width from 3 to 8 cm reduced the deposition thickness by approximately 60% while the current density decreased by only 9%.

Black phosphorus (BP) and its few-layer counterpart, phosphorene, combine an anisotropic two-dimensional lattice, thickness-dependent electronic properties, strong near-infrared response, and chemically accessible phosphorus sites. The same surface chemistry that makes phosphorene attractive also makes it difficult to process and preserve reproducibly. This review focuses mainly on studies published from 2023 through September 2026 and examines how the field has shifted from proof-of-concept exfoliation toward deliberate interface control. Recent progress in liquid and electrochemical exfoliation, bipolar deposition, covalent functionalization, molecular passivation, and removable protective layers is discussed together with applications in Li- and Na-ion batteries, Li-S systems, supercapacitors, electrocatalytic water splitting, photocatalytic hydrogen evolution, CO₂ reduction, drug delivery, phototherapy, tissue regeneration, antibacterial treatment, and biosafety. Across these areas, thickness, defect population, oxidation state, interfacial bonding, and nanosheet accessibility repeatedly determine both performance and failure. Particular attention is given to realistic electrochemical metrics, identification of catalytic active states, batch-to-batch reproducibility, and organ-specific safety. The review closes by outlining practical requirements for moving phosphorene from optimized laboratory demonstrations toward reproducible energy, catalytic, and biomedical technologies.

Current electrochemical energy-storage electrodes still face critical challenges in achieving high stability, safety, and low-emission fabrication of modern large-scale applications. In this work, a binder-free co-electrodeposition approach is developed to directly synthesize multi-metal Prussian blue analogue (MM-PBA) electrodes through a water-based electrochemical deposition/conversion process. By incorporating five transition metals (Co, Cu, Fe, Mn, and Ni) into a single-phase PBA framework, the MM-PBA electrode exhibits multi-metal redox activity with enhanced structural stability. As a result, the MM-PBA electrode delivers a high specific capacitance of 456.6 F g-1 at 5 mV s-1. Furthermore, a hybrid solid-state supercapacitor (HSSC) is successfully assembled using the water-processed MM-PBA cathode, operating within an extended voltage window exceeding 2.0 V. The resulting HSSCs revealed 99% coulombic efficiency, a low equivalent series resistance of ~1.72 Ω cm2, and unpreceded cyclability over 35,000 charge-discharge cycles. Comprehensive structural characterizations, including SEM–EDS, XRD, and FTIR analyses, confirm the formation of a uniform single-phase MM-PBA framework via electrodeposition. These results demonstrate the viability of an environmentally friendly and cost-effective pathway for producing high-performance hybrid solid-state energy storage devices

Recent improvements in flexible pressure sensors have proved valuable for a wide range of applications, including tactile sensing, physiological sensing, and portable healthcare monitoring. Most studies aim to improve the sensitivity of the pressure sensors for monitoring subtle pressure responses, such as pulse waveforms from the wrist artery. This study presents the development of a novel multimodal pressure sensor that combines supercapacitive and piezoresistive sensor modes for simultaneous pulse waveform collection. The individual sensors underwent a fast and low-cost fabrication process, achieving high sensitivity. The supercapacitive pressure sensor utilized tissue paper as a backbone and polymer gel as an electrolyte, while the piezoresistive mode employed a liquid-assisted transfer method with sandpaper as a mold, along with graphene nanoplatelets and multi-wall carbon nanotubes as sensing layers. The piezoresistive sensor exhibited a high sensitivity of 19.8 kPa⁻¹ and stable performance. The supercapacitive sensor demonstrated the highest sensitivity of 2.85 kPa-1 within a pressure range of 16 kPa. When integrated, the multimodal sensor achieved a peak sensitivity of 2 kPa⁻¹ for the piezoresistive mode and 1 kPa⁻¹ for the capacitive pressure mode, enabling the detection of uniform pulse waveforms with intrinsic peaks. Furthermore, the multimodal sensor exhibited stable cyclic performance under a loading of 5000 cycles. The primary application of the multimodal pressure sensor is the simultaneous acquisition of pulse waveforms from the same wrist arterial position using two independent sensing modes. This multimodal sensor holds potential for 24-hour ambulatory blood pressure monitoring, offering advancements in wearable healthcare technology.

This letter reports the design, fabrication, and evaluation of a flexible cross-bar pressure sensor array for real-time high-resolution force mapping, with a primary application in pressure monitoring. Traditional flexible pressure sensors are limited by low spatial resolution and wiring complexity, hindering their use in detailed biomechanical analysis. Here, we introduce a novel plain-weave cross-bar structure, in which copper wire electrodes are interlaced with multilayer Velostat sheets. The sensor array is integrated with an ESP32 microcontroller and a multiplexer to achieve scalable data acquisition and wireless transmission. Calibration tests demonstrate that the sensor exhibits high sensitivity (up to 0.85 kPa⁻¹) in the low-pressure regime (0–2.5 kPa), and reliable response for dynamic foot pressure mapping during walking. The system enables real-time visualization and mapping of pressure distribution across a 6 × 6 array, providing rich data for gait and rehabilitation monitoring. This design improves electrode-material contact uniformity, and reduces noise compared to conventional stacked cross-bar configurations. The combination of a low-cost fabrication approach with the novel plain-weave architecture establishes the key novelty of this work, offering a scalable and customizable platform for wearable biomechanics and health monitoring.

Continuous blood pressure (BP) monitoring provides valuable insight into the body’s dynamic cardiovascular regulation across various physiological states such as physical activity, emotional stress, postural changes, and sleep. Continuous BP monitoring captures different variations in systolic and diastolic pressures, reflecting autonomic nervous system activity, vascular compliance, and circadian rhythms. This enables early identification of abnormal BP trends and allows for timely diagnosis and interventions to reduce the risk of cardiovascular diseases (CVDs) such as hypertension, stroke, heart failure, and chronic kidney disease as well as chronic stress or anxiety disorders. To facilitate continuous BP monitoring, we propose an AI-powered estimation framework. The proposed framework first uses an expert-driven feature engineering approach that systematically extracts physiological features from photoplethysmogram (PPG)-based arterial pulse waveforms (APWs). Extracted features include pulse rate, ascending/descending times, pulse width, slopes, intensity variations, and waveform areas. These features are fused with demographic data (age, gender, height, weight, BMI) to enhance model robustness and accuracy across diverse populations. The framework utilizes a Tab-Transformer to learn rich feature embeddings, which are then processed through an ensemble machine learning framework consisting of CatBoost, XGBoost, and LightGBM. Evaluated on a dataset of 1000 subjects, the model achieves Mean Absolute Errors (MAE) of 3.87 mmHg (SBP) and 2.50 mmHg (DBP), meeting British Hypertension Society (BHS) Grade A and Association for the Advancement of Medical Instrumentation (AAMI) standards. The proposed architecture advances non-invasive, AI-driven solutions for dynamic cardiovascular health monitoring.

Wearable, flexible piezoresistive pressure sensors have garnered substantial interest due to their diverse applications in fields such as electronic skin, robotic limbs, and cardiovascular monitoring. Among these applications, arterial full pulse waveform monitoring stands out as a critical area of research. The emergence of piezoresistive pressure sensors as a prominent tool for capturing pulse waveforms has led to extensive investigations. However, the lack of a linear response while achieving high sensitivity, limited compactness of signal collection systems, and scaling issues are a few potential causes of the gap between research advances and technology market readiness. Here, we present a scalable dual piezoresistive sensor that uses two complementary resistance-changing mechanisms to balance the trade-off between linear response and high sensitivity. This synergic design enables excellent sensitivity of 8.4 kPa^-1 and near linear pressure response. It boasts a fast response time of 95/145 ms for loading and unloading at a pressure of 10.1 kPa. The durability tests, encompassing nearly 5000 two-stage compression cycles, validate the reliable performance of the sensor, even after prolonged use. Leveraging these performance metrics, we developed a high-resolution and compact signal collection device capable of accurately detecting the three distinct peaks associated with the full pulse waveform, including the systolic and reflected diastolic peaks. Moreover, the signal acquisition system incorporates a photoplethysmography sensor, which, when paired with the dual piezoresistive sensor, offers new insights into localized vascular health monitoring. The unique feature of our approach is its ability to perform localized vascular monitoring using multiple sensors placed on different veins. The simultaneous detection of forward- and backward-going pulse waves at the body extremities allows for a comprehensive evaluation of localized vascular health, which is not achievable with a single sensor. Finally, the comparison of wrist pulse waveforms between the compact signal collection device and a standard sourcemeter (such as the Keithley 2460) confirmed that the wearable sensing system is on par with conventional sourcemeters in terms of capturing the typical details of the full pulse waveform (i.e., systolic peak, dicrotic notch, and diastolic peak). This validation underscores the reliability and effectiveness of the developed wearable sensing system for practical and continuous pulse waveform monitoring.

High thermal conductivity and a high breakdown field make diamond a promising candidate for high-power and high-temperature semiconductor devices. Diamond also has a higher radiation hardness than silicon. Recent studies show that diamond has exceptionally large electron and hole momentum relaxation times, facilitating compact THz and sub-THz plasmonic sources and detectors working at room temperature and elevated temperatures. The plasmonic resonance quality factor in diamond TeraFETs could be larger than unity for the 240–600 GHz atmospheric window, which could make them viable for 6G communications applications. This paper reviews the potential and challenges of diamond technology, showing that diamond might augment silicon for high-power and high-frequency compact devices with special advantages for extreme environments and high-frequency applications.