A MEMS-based Fractal-Laplace catheter electrode facilitating integrated pulsed field ablation (PFA), real-time electrocardiographic (ECG) monitoring, and cardiac pacing is introduced. The electrode utilizes concentric Laplace rings for electric-field confinement alongside an internal fractal microelectrode that improves current transfer and field penetration, enabling deep and spatially focused myocardial ablation at an exceptionally low operational voltage of 100 V. The design resolves enduring trade-offs among lesion depth, accuracy, and voltage. In vitro potato-tissue experiments demonstrate a 44 % augmentation in lesion depth and a 28 % enhancement in spatial accuracy compared to conventional electrodes. In vivo rat epicardial investigations reveal transmural lesion creation, concurrent ECG monitoring, and steady pacing, underscoring the potential to integrate diagnosis and treatment in future less invasive cardiac therapies.

This paper reports an implantable nanoscale neural probe (INNP) developed through a layer-by-layer deposition process based on MEMS manufacturing technology and a precision machining technique based on atmospheric microplasma jet, marking the first successful application of solid-state sensing methods for in vivo intracellular electrophysiological analysis. The exposed tip lengths of INNPs are precisely controlled to as low as $\sim 40$ nm, with diameters of $\sim 100 \text{nm}$. Electrochemical stability, biocompatibility and minimal invasiveness of INNP during acute implantation were validated. Significant recordings of in vivo intracellular action potentials and ion currents were acquired: The amplitude and half-width of action potential spikes were $\sim 8.31 \text{mV}$ and $\sim 1.11 \text{ms}$ respectively, with the amplitude of superimposed action potential spikes reaching up to $\sim 70 \text{mV}$, while the amplitudes for fast electrical synaptic currents and postsynaptic currents (PSCs) ranged from tens of pA to several nA, with halfwidths of $\sim 0.10 \text{ms}$ and $\sim 2.24 \text{ms}$ respectively. Notably, pain stimuli resulted in a significant increase in amplitudes of negative spikes of PSCs along with a significant decrease in half-widths, and triggered an evident generation of positive spikes. This work represents a significant breakthrough in the development of next-generation nanoscale implantable brain-computer interface (BCI) devices aimed at single-neuron intracellular analysis.

Spinel-structured Ni-Co-Mn ceramics are widely employed in thermistor-based temperature sensing, but their typically high resistance and large dimensions hinder miniaturization and integration with modern IC technologies. In this work, we demonstrate that Fe doping can effectively tailor the resistance-temperature characteristics of Ni-Co-Mn ceramics. The physical mechanisms underlying the Fe-induced phase evolution and electrical properties are systematically investigated. With increasing Fe dopant, new spinel phases—NiFe2O4 and Ni(Mn,Fe)2O4—emerge, leading to a significant rise in the proportion and concentration of Mn³⁺/Mn⁴⁺ mixed-valence cation pairs. This change enhanced small-polaron hopping conduction mechanism. Meanwhile, Fe incorporation reduces the amount of residual NiO, further improving electrical conductivity. A compact miniaturized bead-type ceramic temperature sensor with a diameter of approximately 800 μm was fabricated using a microelectronic dispensing process, with different Fe doping concentrations introduced. The results demonstrate that precisely controlled Fe substitution provides an effective and low-cost approach to reducing the resistivity of Ni–Co–Mn spinel thermistors without sacrificing sensitivity or stability. This strategy offers a promising pathway for the development of low-power, miniaturized temperature sensors for next-generation intelligent and highly integrated systems.

Inspired by marine mammals' exceptional low-frequency hearing, we present a biomimetic cochlea-like scandium-doped aluminum nitride MEMS hydrophone (BCMH) for miniaturized, high-fidelity underwater acoustic sensing. The device employs a compact spiral stress-sensing architecture, achieving a flat receiving sensitivity of-167.7 +/- 1.1 dB (re V/mu Pa), excellent omnidirectivity +/- 0.5 dB vertical and +/- 0.9 dB horizontal, with lower than the self-noise base of the first-order sea state. Enabled by bioinspired cochlear geometry and advanced piezoelectric materials, it offers a practical, high-performance solution for low-frequency seismic monitoring and next-generation underwater acoustic sensing, surpassing conventional hydrophone technologies.

This work presents a piezoelectric MEMS hydrophone inspired by the organ of Corti in the cochlear structure, nature's masterful sound-receiving apparatus. The device employs $\text{Sc}_{0.3} \text{AlN}_{0.7}$ as the piezoelectric material for enhanced transduction efficiency. Under acoustic excitation, the biomimetic membrane generates opposing electrical potentials across its surface, mimicking biological signal conversion. A differential readout scheme from a shared top electrode coherently sums these counteracting charges, effectively superimposing the potentials to boost output fidelity. This innovative configuration delivers exceptional sensitivity of $-212.6 \pm$ 1.2 dB (re $1 \mathrm{V} / \mu \text{Pa}$) across the low-frequency band of 20 Hz to 2 kHz, exhibiting remarkable flatness and superior low-frequency performance, making it ideal for advanced underwater acoustic sensing applications.

Neural probes targeting single neurons are instrumental in overcoming the ambiguity associated with population-averaged signals and the attenuation of extracellular signals to reveal the fundamental units of neural coding. However, current neural probes are limited by resolution, structural design, and micro/nanotechnology, making it challenging to penetrate single neurons in vivo to directly record various neural signals. Here, we report a multilayer carbon-structured nanoprobe (MLCNP) for intracellular electrophysiological and chemical recordings in vivo. The sensing layers, composed of graphene and feather-shaped carbon nanowires (FCNW), and the protective layer of nanodiamond are prepared via microwave plasma chemical vapor deposition. The controlled exposure of nanotips, roughening of FCNW sensing layers, and adsorption of Pt nanoparticles on their surface are achieved through microplasma jet branch etching (MPJBE). The multilayer carbon structures and the MPJBE treatment significantly enhance the cathodic charge, peak cathodic current and sensitivity to dissolved O2 of nanoprobes. The MLCNP with a tip diameter of approximately 70 nm and an exposed sensing area length of about 900 nm, demonstrates good cytocompatibility, minimal invasive damage, and selective O2-sensing capabilities. Finally, intracellular electrophysiological signals and variations in O2 concentration, along with other potential biochemical signals, are successfully recorded in vivo, and the effects of pain stimulation on electrophysiological spikes were analyzed. The developed nanoprobe based on the new materials and processes and its successful acquisition of electrical and biochemical signals at the single-neuron level in vivo, hold profound significance for a deeper understanding of the intrinsic mechanisms of the nervous system.

Existing microfabrication processes are generally characterized by unavoidable residues and thermal damage, lack of material selectivity, and limited controllability, which significantly impact the texturing quality of high-performance coatings such as diamond-like carbon (DLC). Hence, this paper reports a maskless modulation strategy for curved surface based on cold atmospheric plasma jet (CAPJ) for gentle and controllable sinusoidal texturing of functional coatings. Through the development of multi-freedom motion and monitoring systems along with the regulation of key process parameters, the consistency and uniformity of graphical modulation on DLC surfaces are greatly enhanced. The surface morphology and composition changes of etched dots, lines, and sinusoidal textures were comprehensively characterized and analyzed at atomic and molecular scales by SEM, SDM, EDS, XPS, XRD, FTIR, profilometer, and Raman spectrometer, demonstrating the exceptional properties of our strategy in terms of selectivity, residue-free, and absence of thermal damage, further achieving high-quality on-demand modulation of standard multi-period sinusoidal profiles with amplitudes as low as 60 nm on curved DLC. The developed novel micro/nanofabrication process holds significant potential for gentle and selective surface treatment in interdisciplinary MEMS devices.

This paper reports an agile millimeter-scale microrobot driven by single piezoelectric actuator, which achieves eight programmable locomotion modes at different driving frequencies, including forward, backward, lateral, and diagonal trajectories. The microrobot with its weight of only 0.12 g achieves the maximum forward velocity of $82.4 \text{cm} / \mathrm{s}(84.1 \text{BL} / \mathrm{s})$. Moreover, it operates with a minimum driving voltage of 5 V $\mathrm{P}-\mathrm{P}$, thereby demonstrating superior agility and energy efficiency compared with multi-actuator robots. Beyond high-speed locomotion, the microrobot exhibits remarkable load-carrying capability (more than 38.6 times its body weight), as well as the ability to climb and navigate confined micropipes. These combined features enhance mobility, obstacle-avoidance capacity, and functional adaptability, offering a promising strategy for frequency-programmable piezoelectric microrobots in rescue exploration and micromanipulation.

MEMS vector hydrophones are poised to become the core devices of miniaturized underwater acoustic sensing. However, existing MEMS vector hydrophones suffer from low sensitivity and shallow concave point depth, which hinders longrange detection. In this work, we present an axisymmetric bionic seal whisker-type piezoelectric MEMS vector hydrophone (ASWVH) that leverages bioinspired geometries and stressconcentration regions to amplify piezoelectric output, yielding enhanced directivity and high sensitivity. The optimal microstructure dimensions for ASWVH were determined using COMSOL 5.6 simulations. The biomimetic seal whisker structure not only ensures an operational frequency bandwidth of 20-2000 Hz but also expands the effective acoustic reception area, thereby further enhancing sensitivity. The unique wavy bionic sealing whisker shape provides high sensitivity, and the measured X- and Y-axis sensitivities are -171.7 and -173.2 dB @ 2 kHz (ref. 1 V/mu Pa), respectively. Moreover, the device exhibits an exceptional "8"-shaped directivity pattern with concave point depth exceeding 40 dB in both channels, rendering it well suited for high-precision passive underwater detection.

Excellent mechanical properties and force-electric coupling are essential for flexible conductive hydrogels, enabling their applications in soft robotics, wearable sensors, and human-machine interfaces. However, such hydrogels often face a fundamental trade-off between mechanical strength and electrical sensitivity. Inspired by the "soft-hard" architecture strategy in biological mechanical tissues and mussel-inspired multimode interacting mechanisms, we report the fabrication of a composite conductive hydrogel with enhanced mechanical strength, fatigue resistance, universal surface adhesion, and highly sensitive mechano-sensing capabilities by incorporating tannic acid-modified cellulose nanocrystals (CNC@TA) into an interpenetrating polyacrylamide/poly(vinyl alcohol)/poly(acrylic acid)/Al3+ multinetwork hydrogel matrix. The TA functionalization provides the CNCs with abundant cross-linking and interaction sites, enabling strong bonding with the surrounding matrix through physical entanglements, hydrogen bonding, π-π stacking, and coordination interactions. The hydrogel exhibits universal adhesion to various substrates and achieves well-performed mechanical property with elongation up to 765%, tensile strength around 83 kPa, and toughness around 276 kJ/m3. Simultaneously, the coordinated Al3+ ions provide the hydrogel with excellent ionic conductivity and a high strain sensitivity (gauge factor of up to 2.7). With superior mechanical properties and force-electric coupling performance, this hydrogel holds broad application potential in flexible electronics, human-machine interaction devices, and biomimetic materials.

To enhance low-frequency detection sensitivity and achieve omnidirectionality in underwater acoustic sensors, this paper reports a hexagonal array piezoelectric MEMS acoustic sensor (HAAS). The HAAS comprises six identical triangular cantilever beams symmetrically arranged in a regular hexagon. This array configuration enables signal superposition to boost sensitivity, while the multi-degree-of-freedom vibrating membrane promotes omnidirectionality in underwater acoustic detection. The distinctive hexagonal array structure imparts exceptionally high sensitivity in the frequency range of 630Hz to 1.6kHz (-161.2 dB at fixed 1.6kHz,ref.1 V/Pa) and superior omnidirectional directivity, with nonuniformities of +/- 0.5 dB in the horizontal plane and +/- 0.3 dB in the vertical plane at 2 kHz. Experimental results demonstrate the substantial potential of the HAAS for applications in underwater biological activity monitoring, communication, and resource exploration.[2025-0191]

Conventionally designed edge-bound type piezoelectric Micro Electro Mechanical Systems (MEMS) speakers with Si supporting layer still suffer from the problem of low sound pressure level (SPL) and high total harmonic distortion (THD). In this paper, we demonstrate a center-bound type piezoelectric MEMS speaker based on flexible supporting layer, which meets the minimum SPL requirement for human hearing, and achieves a lower THD over a wider continuous frequency band compared with the reported state-of-the-art works, and demonstrates good reliability and durability. Test results in an acoustics test adaptor show that at a driving voltage of 1 Vrms, greater than 52 dB SPLs are obtained in the human audible range of 20 Hz-20 kHz, basically meeting the minimum auditory requirements for human beings. The applicable working frequency range for THD of this device spans the medium and high frequency band of 500 Hz-20 kHz. Compared with state-of-the-art reported works, it achieves a THD of <= 5% over a significantly wider continuous frequency range. Moreover, this speaker produces no abnormal sound, shows no fracture after dropping from a height of 5 meters, and maintain at least 90% of the SPLs after playing music continuously for 100 hours. The proposed center-bound type piezoelectric MEMS speaker with flexible supporting layer is expected to drive its own development and practical application by offering new perspectives and design concepts to researchers and enterprises.

Long-term monitoring and early diagnosis of cardiovascular diseases are crucial to reducing morbidity and mortality. Given the challenges of electrocardiogram monitoring due to stringent environmental requirements and high costs, leveraging wearable pulse signals for cardiovascular disease detection becomes a key solution. Here, we introduce an interphase-induced stress modulation mechanism to fabricate a high-performance flexible piezoelectric ceramic sensor via a one-step mechanical thinning strategy, which exhibits a high longitudinal piezoelectric coefficient of 280 pC/N, and an outstanding thickness-to-diameter ratio of similar to 0.01. Theoretical analysis and experiments show that the metal interphase between the brittle ceramic and hyperelastic substrate creates a stress gradient, enabling large, reversible bending. Furthermore, we developed a wireless piezoelectric sensing system based on the double-feature temporal convolutional network (DTCN) to detect common cardiac diseases from piezoelectric pulse signals. This approach enables continuous pulse monitoring for early prevention and long-term monitoring of pacemaker patients.

The ultrasonic cavitation effect plays a critical role in non-invasive medical treatment. To develop a flexible ultrasonic cavitation patch, it is necessary to enhance the emission intensity of the transducer to reach the threshold sound pressure at low operating voltages, while simultaneously minimizing potential risks to surrounding tissues. This paper presents a piezoelectric ultrasonic micro-patch with low operating voltage and high safety. The device is fabricated using microfabrication techniques to obtain thin piezoelectric ceramics, which are then embedded in an elastic base layer to ensure optimal adhesion. A ring-island structure is further designed to integrate both ultrasonic emission and reception functions within a single patch. Sound field simulation and experimental results indicate that, under a driving voltage of 25 Vpp, the emitted ultrasonic intensity reaches 90 kPa, enabling the observation of bubble generation and oscillation in liquids. The mechanical index is only 0.11. To enhance safety, an ultrasonic switch circuit was designed to ensure the temperature remains below 38 degrees C and the spatial-peak temporal-average intensity is less than 100 mW/cm2. This study contributes significantly to the advancement of wearable ultrasound therapy.

Wearable human–machine interaction systems are limited by spatial undersampling, in which sparse sensing nodes cannot resolve complex local physiological signals, reducing the accuracy and robustness of multitask decoding. To overcome this limitation, a spatial information enhancement framework (SIEF) is proposed by integrating local biomechanical propagation priors with physics-informed neural networks. The missing spatial information under sparse sampling conditions is reconstructed through collaborative modeling of physical piezoelectric sensing nodes and virtual reconstruction nodes without increasing the number of hardware channels. Thus, this framework can achieve unified decoding of motions, silent words, continuous sentences, and affective states via a single sensing gateway, improving the overall multitask recognition accuracy from 83.3% to 97.52%. Furthermore, a lightweight model is deployed on a microcontroller for real-time edge inference, reducing the system communication latency from 777 ms to 32 ms. To mitigate semantic ambiguity in silent speech recognition caused by similar articulation patterns, a foundation large language model is further adapted to the characteristics of piezoelectric signals, increasing the recognition accuracy of easily confused words from 50.0% to 99.5%. Beyond that, SIEF also supports high-level semantic and affective interaction, indicating a scalable, real-time, and practically applicable route toward next-generation wearable human–machine interaction systems. One sentence summary A physics-informed framework enhances spatial information for unified action, speech, and affect decoding and interaction.

Piezoelectric MEMS hydrophones possess inherent advantages in miniaturization for underwater acoustic sensing. However, most existing designs employ top–bottom electrode configurations that collect only a single polarity of piezoelectric charge, limiting the achievable output amplitude. In this work, a high sensitivity and high stability piezoelectric MEMS hydrophone based on a cross short-beam and back-island (CBBI) architecture is proposed. The device introduces a differential electrodes strategy to exploit the spatial distribution of piezoelectric stress. The cross-shaped short beams generate pronounced stress concentration with opposite polarities, and the differential electrodes configuration enables simultaneous extraction and superposition of opposite-polarity charges, thereby enhancing acoustic pressure sensitivity. The device achieves a sensitivity of −169.2 dB ± 1 dB within 10 Hz-2 kHz and a directional non-uniformity of 0.8 dB. The Parylene C coated hydrophone operates stably under hydrostatic pressures up to 20 MPa owing to the pressure equalization effect of the annular trench. The device exhibits excellent environmental robustness, with sensitivity variation confined to −0.229 dB over a temperature range of 0 °C to 95 °C. A backside island improves linearity, with a maximum nonlinearity of 2.33%. Experimental results further demonstrate enhanced transient response and improved signal recognition capability in both air and underwater environments, indicating strong potential for high performance acoustic sensing in complex deep-sea applications.

This paper reports the fabrication and characterization of a piezoresistive pressure sensor based on oxygen-doped zirconium nitride ($\mathrm{O}-\text{ZrN}$) thin film. The piezoresistive effect in O-ZrN thin film is experimentally demonstrated for the first time, enabling its implementation as a pressure sensor through stress-dependent resistivity near the metalinsulator transition. With transverse and longitudinal gauge factors of $\text{GF}_{\mathrm{t}}=-707$ and $\text{GF}_{1}=-302, \mathrm{O}-\text{ZrN}$ thin film exhibits approximately 6 to 7 times higher transverse piezoresistance and about 3 times higher longitudinal piezoresistance compared to doped silicon, as measured by four-point bending at room temperature. The $\mathrm{O}-\text{ZrN}$ thin film piezoresistive pressure sensor achieved a sensitivity of $0.91 \text{mV} / \mathrm{V} / \text{kPa}$ with a flat membrane and $0.61 \text{mV} / \mathrm{V} / \text{kPa}$ with a cross-beam structure, demonstrating the feasibility of highly sensitive piezoresistive sensors based on phasetransition materials.

This work presents a cryogenic temperature sensor fabricated using a self-prepared ruthenium oxide (RuO 2) slurry rather than conventional commercial pastes. The tailored formulation enables precise control over microstructure and conduction pathways, resulting in markedly enhanced sensitivity and stability at deepcryogenic temperatures. At 1 K, the sensor achieves a sensitivity of $1769 \Omega/\mathrm{K}$, which is over five times that of the widely used RX-102B-RS ($316 \Omega/\mathrm{K}$) along with a significantly higher TCR of 0.0837/K compared to 0.0497 /K, a significantly higher Sa of 0.1284 compared to 0.0517. These results show that integrating optimized slurry chemistry with MEMS-compatible processing sets a new benchmark in cryogenic sensing and enables a scalable route to reproducible, high-performance devices for lowtemperature applications.

This paper reports on a pH -nanosensor fabricated through layer-by-layer sputtering, atomic layer deposition (ALD) and microplasma jet branch etching (MPJBE) techniques, which achieved unprecedented recordings of abnormal intracellular pH levels in fresh brain tissue from inflammatory pain mice. The pH -nanosensor features a complete coverage of a thin $\text{Al}_{2} \mathrm{O}_{3}$ layer on large-surface-area $\text{IrO}_{\mathrm{x}}$ nanowires outside its tip collection site, with a tip resolution of the pH -nanosensor below 300 nm and an exposed length at the submicron scale, ensuring that the detection area is entirely intracellular. Electrochemical testing indicates that the introduction of $\text{Al}_{2} \mathrm{O}_{3}$ layer enhances the stability of the pH -nanosensor after multiple insertions into physiological environments while minimally affecting superior electrochemical properties, pH sensing sensitivity and reversibility of $\text{IrO}_{\mathrm{x}}$. Moreover, the pH -nanosensor exhibits good pH -selectivity, cytocompatibility, and minimal penetration damage. Finally, by inserting the pH -nanosensor into pyramidal neurons within the anterior cingulate cortex (ACC), a region associated with pain perception, intracellular pH values from complete Freund's adjuvant (CFA)-induced inflammation brain slices were recorded. The proposed pH -nanosensor holds significant research value for detecting biochemical markers at single-neuron scales to facilitate early diagnosis and monitoring of diseases.