Flexible and high-responsive phototransistors are highly demanded for wearable near-infrared (NIR) image sensors. Hybrid phototransistors utilizing the photogating effect, featuring separate sensing and transport layers, show considerable potential. However, optimizing the photogating effect remains a significant challenge. Here, we proposed a facile interface reduction processing to oxide semiconductors, enabling high-performance In2O3/Y6 heterojunction phototransistors with enhanced photo-gating effect for NIR sensing.

Neuromorphic visual processing hardware mimics key functions of the human visual system, including static image sensing and processing, as well as the perception and prediction of moving targets. However, conventional complementary metal-oxide semiconductor (CMOS) platforms face significant challenges such as power consumption and processing delays. Herein, a 64 x 64 active-matrix photosensor array (AM-PA) is developed with a one-transistor-one-photodetector architecture, by integrating metal-oxide thin-film transistors with monolayer MoS2 photodetectors. By modulating the intrinsic defects serving as charge-trapping centers within the MoS2 film, the AM-PA exhibits configurable conductance plasticity in response to optical stimuli. This system enables in-array visual sensing and processing functionalities: static image sensing and pre-processing to reduce noise, prediction of dynamic spatiotemporal patterns, and accurate trajectory forecasting for complex motion scenarios. These results demonstrate the feasibility of the AM-PA as a promising platform for neuromorphic visual systems.

Neuronal tuning curves are the important characteristics of sensory neurons for encoding stimulus variables. However, it is challenging to achieve configurable neuronal tuning curves with nanoscale neuron devices. In this brief, we successfully demonstrate biomimetic neuronal tuning curves with NbOx Mott memristor by virtue of its electrically configurable spiking behaviors. The NbOx Mott neuron not only realizes probabilistic spiking but also exhibits configurable Gaussian spiking distribution. This enables the emulation of the key features of biological tuning curves, feasible for hardware implementation of artificial sensory neural network with high biological fidelity.

Artificial synapses capable of optical sensing and synaptic functions are essential for developing neuromorphic visual systems. We utilized quantum dots (QDs)/oxide heterostructure to achieve bidirectional synaptic weight modulation under ultraviolet and infrared light by the change of depletion layer width of the p-n junction. Such an all-optically controlled artificial synapse shows a promising prospect for future neuromorphic visual systems.

Color spiking encoding and opponent preprocessing are critical for energy-efficient object perception in the human visual system. Emulating the retina and brain's integration of spatial and chromatic spiking signals holds promise for enhancing the efficiency of vision sensors. Here, we introduce an artificial visual neuron array that generates excitatory or inhibitory spiking responses to specific wavelengths with orientation selectivity. The neuron array can function as double-opponent receptive fields for spatial-chromatic opponent preprocessing to color signals, emulating the neural pathway from the retina to the cortex. With the color spiking preprocessing function of the neuron array, the recognition accuracy is improved almost twofold compared to direct perception of underexposure objects, and the noise robustness is also strengthened. This architecture leverages biological mechanisms for simultaneous spike encoding and antagonistic preprocessing of color information, offering the potential for highly efficient neuromorphic vision systems.

Molybdenum disulfide (MoS 2 ) has drawn extensive interest due to its excellent performance as a 2D n‐type semiconductor. However, achieving high‐performance devices based on p‐type MoS 2 , which is crucial for complementary field effect transistors (CFETs) and neuromorphic computing applications, remains limited. Here, an optoelectronic reservoir computing (RC) based on a p‐type Nb‐doped MoS 2 device is reported. The device shows p‐type transistor characteristics with a high on/off current ratio exceeding 10 6 , low subthreshold swing ( SS ) of 234 mV dec −1 , notable on‐state current of 12 µA µm −1 , along with robust cyclic performance and ambient stability. Importantly, the optically tunable facilitated and depressed conductance arises from Nb‐vacancy defect states, confirmed by Kelvin probe force microscopy measurement. Furthermore, the device enables 100% motion recognition across eight directions and functions as a reservoir to map feature information from various sequential optical inputs, exhibiting computing capability in pattern recognition with an accuracy of 88%.

Wearable sensors designed for continuous, non‐invasive monitoring of physicochemical signals are important for portable healthcare. Oxide field‐effect transistor (FET)‐type biosensors provide high sensitivity and scalability. However, they face challenges in mechanical flexibility, multiplexed sensing of different modules, and the absence of integrated on‐site signal processing and wireless transmission functionalities for wearable sensing. In this work, a fully integrated wearable oxide FET‐based biosensor array is developed to facilitate the multiplexed and simultaneous measurement of ion concentrations (H+, Na+, K+) and temperature. The FET‐sensor array is achieved by utilizing a solution‐processed ultrathin (≈6 nm thick) In2O3 active channel layer, exhibiting high compatibility with standard semiconductor technology, good mechanical flexibility, high uniformity, and low operational voltage of 0.005 V. This work provides an effective method to enable oxide FET‐based biosensors for the fusion of multiplexed physicochemical information and wearable health monitoring applications.

Human visual neurons rely on event-driven, energy-efficient spikes for communication, while silicon image sensors do not. The energy-budget mismatch between biological systems and machine vision technology has inspired the development of artificial visual neurons for use in spiking neural network (SNN). However, the lack of multiplexed data coding schemes reduces the ability of artificial visual neurons in SNN to emulate the visual perception ability of biological systems. Here, we present an artificial visual spiking neuron that enables rate and temporal fusion (RTF) coding of external visual information. The artificial neuron can code visual information at different spiking frequencies (rate coding) and enables precise and energy-efficient time-to-first-spike (TTFS) coding. This multiplexed sensory coding scheme could improve the computing capability and efficacy of artificial visual neurons. A hardware-based SNN with the RTF coding scheme exhibits good consistency with real-world ground truth data and achieves highly accurate steering and speed predictions for self-driving vehicles in complex conditions. The multiplexed RTF coding scheme demonstrates the feasibility of developing highly efficient spike-based neuromorphic hardware.

Threshold switching (TS) devices based on NbO 2 Mott memristors have become important candidates for constructing artificial neurons in neuromorphic computing hardware. However, there is lack of research on the impact of device structure on performance of NbO x neurons. In this letter, NbO x -based TS devices are experimentally achieved by utilizing coplanar electrodes. We also propose a method to improve the reliability by using the passivation layer that can prevent the oxidation of the NbO x . Nonlinear neural dynamics are experimentally implemented using artificial neuron circuits. The success of coplanar device facilitates the future realization of multi-terminal NbO x neurons and provides a basis for further investigation on TS mechanism of NbO x Mott memristors.

Optoelectronic synapses are desirable for avoiding hardware latency and achieving high bandwidth and low crosstalk. We utilized the trapping and de-trapping effect in the inorganic-organic heterojunction to achieve optically controlled weight modulation for synaptic functions including long-term potentiation and depression depending on the incident light wavelength. The artificial synapses with optical responsivity could implement both sensing and processing functions, promising for constructing optogenetics-inspired neuromorphic vision networks.

The human retina perceives and preprocesses the spectral information of incident light, enabling fast image recognition and efficient chromatic adaptation. In comparison, it is reluctant to implement parallel spectral preprocessing and temporal information fusion in current complementary metal-oxide-semiconductor (CMOS) image sensors, requiring intricate circuitry, frequent data transmission, and color filters. Herein, an active-matrix synaptic phototransistor array (AMSPA) is developed based on organic/inorganic semiconductor heterostructures. The AMSPA provides wavelength-dependent, bidirectional photoresponses, enabling dynamic imaging and in-sensor spectral preprocessing functions. Specifically, near-infrared light induces inhibitory photoresponse while UV light results in exhibitory photoresponse. With rational structural design of the organic/inorganic hybrid heterostructures, the current dynamic range of phototransistor is improved to over 90 dB. Finally, a 32 × 64 AMSPA (128 pixels per inch) is demonstrated with one-switch-transistor and one-synaptic phototransistor (1-T-1-PT) structure, achieving spatial chromatic enhancement and temporal trajectory imaging. These results reveal the feasibility of AMSPA for constructing artificial vision systems.

Flexible tactile sensor arrays are crucial to enable robotics with human-like tactile perception. However, there is a trade-off between high density and sensitivity in sensor arrays, because signal crosstalk among adjacent pixels gradually becomes serious with increased pixel density. In this work, we demonstrate a flexible active-matrix (AM) tactile sensor array (TSA) with both high pixel density and sensitivity, by monolithically integrating a 64 x 64 lanthanum-doped indium zinc oxide (Ln-IZO) thin-film transistor (TFT) array (4096 pixels, 1 x 1 cm2) with a hierarchically micro-/nanostructured high pressure-sensitive film. The flexible AM-TSA exhibits a high spatial resolution of 150 um, high in-array tactile sensitivity of 51 kPa-1, fast response/recovery time (51/32 ms), a low detection limit of 2.5 Pa, and robust mechanical stability, feasible for applications in tactile robotics.

Artificial spiking neurons capable of interpreting ionic information into electrical spikes are critical to mimic biological signaling systems. Mott memristors are attractive for constructing artificial spiking neurons due to their simple structure, low energy consumption, and rich neural dynamics. However, challenges remain in achieving ion-mediated spiking and biohybrid-interfacing in Mott neurons. Here, a biomimetic spiking chemical neuron (SCN) utilizing an NbOx Mott memristor and oxide field-effect transistor-type chemical sensor is introduced. The SCN exhibits both excitation and inhibition spiking behaviors toward ionic concentrations akin to biological neural systems. It demonstrates spiking responses across physiological and pathological Na+ concentrations (1-200 × 10-3 m). The Na+-mediated SCN enables both frequency encoding and time-to-first-spike coding schemes, illustrating the rich neural dynamics of Mott neuron. In addition, the SCN interfaced with L929 cells facilitates real-time modulation of ion-mediated spiking under both normal and salty cellular microenvironments.

Interfacial hydrogelation of peptides gated on the semiconductor channel has yet to be explored in surface chemistry and field-effect transistor-based biosensors (bio-FETs). This work reports the first example of peptidic hydrogel gated bio-FET by surface assisted self-assembly for label-free and real-time monitoring of the glucose with low limit of detection, excellent sensitivity, and good stability in mouse serum. The boric acid-containing peptide forms a hydrogel layer on the surface of In2O3, which interacts with glucose reversibly and generates boronate anions to influence the semiconductor's conductivity. The results also indicate the superiority of hydrogel gated bio-FET for real-time monitoring of glucose in complex environments and serve as a wearable device. This work illustrates a simple and fundamental strategy for integrating peptidic hydrogel with bio-FET for the real-time detection of analytes.

Flexible active-matrix sensor arrays have attracted attention for their promising application in soft robotics, health monitoring, and human-machine interfaces. Metal oxide thin film transistors (TFTs) are suitable as the backplane to construct sensor arrays owing to the merits of high mobility, low-temperature processability, and low off-state leakage current. Here, we report a cost-effective solution-processed method to fabricate high-performance metal oxide TFTs. A flexible active-matrix pressure sensor array that can endow robots with tactile perception ability is achieved by integrating the pressure-sensitive materials with oxide TFTs.

It is vital to acquire real‐time pH signals with high resolution as pH variation can reflect important information regarding health status and physiological environment. Field‐effect transistor (FET)‐based biosensors (bio‐FETs), a kind of potentiometric sensor, are being rapidly developed for pH detection due to their advantages of high sensitivity, low temperature dependence, and high portability. More importantly, the high scalability of bio‐FETs renders them applicable for achieving high spatial resolution in pH sensing. In this review paper, the design, operation principle, and critical characteristics of the FET‐based pH sensor are introduced. Then, the recent progress in pH mapping with FET sensor arrays, including static array where a sensor pixel is directly addressed by wiring, and active‐matrix array where a sensor pixel is accessed by additional switching FETs, is presented. Last, typical examples of pH sensor arrays in biomedical applications, such as health monitoring and DNA sequencing and elongation are presented.

Bio-inspired neuromorphic vision sensors, integrating optical sensing, and processing functions have attracted significant attention for developing future low-power and high-efficiency imaging systems. However, the compulsory electrical signal modulation to achieve inhibitory behaviors in most reported neuromorphic vision sensors results in additional hardware and computational latency. Herein, bidirectional photoresponsive optoelectronic synapses based on In2O3/Al2O3/Y6 phototransistors are achieved, realizing all-optical-configured synaptic weight updates enabled by dual photogates. The inhibitory and excitatory photoresponses originate from the photogating effects provided by trapped photogenerated electrons in Al2O3 under near-infrared light and the ionized oxygen vacancies in In2O3 under ultra-violet light, respectively. The bidirectional phototransistor illustrates outstanding optoelectronic synaptic characteristics with low nonlinearity and asymmetry, demonstrating high efficiencies in both preprocessing and postprocessing tasks, such as noise reduction, contrast enhancement, and pattern recognition. The proposed dual-photogate optoelectronic synapses provide effective strategies to construct high-efficiency neuromorphic vision sensors and in-sensor computing systems.

Amorphous oxide semiconductors, especially indium gallium zinc oxide (IGZO), have been widely studied and obtained significant progress in flexible thin-film transistors (TFTs) due to the high carrier mobility and low deposition temperature. However, a further annealing step is generally required to activate electrical properties and improve the device performance, which limited their applications in flexible electronics. In this study, we achieved flexible TFTs and arrays using co-sputtered IGZO and indium tin oxide (ITO) as channels deposited at room temperature without post-annealing. It was found that better transistor switching properties could be effectively achieved by regulating the sputtering power of ITO in the co-sputtered deposition. The device performance is comparable to that of the conventional oxide TFTs with high annealing temperatures (⩾300 °C), exhibiting a high saturation mobility ( μ sat ) of 15.3 cm 2 V −1 s −1 , a small subthreshold swing ( SS ) of 0.21 V dec −1 , and a very high on–off ratio ( I on/off ) of 10 11 . In addition, a 12 × 12 flexible TFT array was achieved with uniform performance owing to the low-temperature processing advantage of this technique. The flexible TFTs exhibited robust mechanical flexibility with a minimum bending radius of 5 mm and bending cycles up to 1000. Furthermore, an inverter based on co-sputtered IGZO and ITO was demonstrated with the maximum gain of 22. All these achievements based on the proposed TFTs without post-annealing process are expected to promote the applications in advanced flexible displays and large-area integrated circuits.

Optoelectronic synaptic devices capable of processing multiwavelength inputs are critical for neuromorphic vision hardware, which remains an important challenge. Here, we develop a bidirectional synaptic phototransistor based on a two-dimensional ferroelectric semiconductor of α-In2Se3, which exhibits bidirectional potentiated and depressed synaptic weight update under optical pulse stimulation. Importantly, the bidirectional optoelectronic synaptic behavior can be extended to multiwavelengths (blue, green, and red light), which could be used for color recognition. The mechanism underlying the bidirectional synaptic characteristics is attributed to the gate-configurable barrier heights as revealed by the Kelvin probe force microscopy measurement. The α-In2Se3 device exhibits versatile synaptic plasticity such as paired-pulse facilitation, short- and long-term potentiation, and long-term depression. The bidirectional optoelectronic synaptic weight updates under multiwavelength inputs enable a high accuracy of 97% for mixed color pattern recognition.

High-resolution mapping of pH can provide vital physiological information in environmental and biomedical applications. In this work, we develop active-matrix potentiometric sensors that integrate pH sensing and mapping capabilities by utilizing field-effect transistor (FET) sensors based on solution-processed oxide semiconductors. The FET sensors exhibit excellent electrical and pH sensing performance, characterized by high uniformity, low operating voltage (0.05 V), near-Nemst-limit sensitivity (59.4 mV/pH), and minimal drift rate (L2 mV/h). These characteristics enable the successful integration of a 16 × 16 active-matrix FET sensor array for high-resolution pH mapping. Furthermore, a transparent FET sensor array is achieved for bio-interface applications, where both the morphology and cellular microenvironment of living cells can be monitored. Our study presents an effective alternative approach beyond CMOS to realize active-matrix pH sensor arrays.