Piezotronic neuromorphic devices: principle, manufacture, and applications

Neuromorphic devices capable of emulating biological synaptic behaviors are crucial for implementing brain‐like information processing and computing. Emerging 2D ferroelectric neuromorphic devices provide an effective means of updating synaptic weight aside from conventional electrical/optical modulations. Here, by further synergizing with an energy‐efficient synaptic plasticity strategy, a multimodal mechano‐photonic synaptic memory device based on 2D asymmetric ferroelectric heterostructure is presented, which can be modulated by external mechanical behavior and light illumination. By integrating the asymmetric ferroelectric heterostructured field‐effect transistor and a triboelectric nanogenerator, the mechanical displacement‐derived triboelectric potential is ready for gating, programming, and plasticizing the synaptic device, resulting in superior electrical properties of high on/off ratios (> 107), large storage windows (equivalent to ≈95 V), excellent charge retention capability (> 104 s), good endurance (> 103 cycles), and primary synaptic behaviors. Besides, optical illumination can effectively synergize with mechanoplasticity to implement multimodal spatiotemporally correlated dynamic logic. The demonstrated multimodal memory synapse provides a facile and promising strategy for multifunctional sensory memory, interactive neuromorphic devices, and future brain‐like electronics embodying artificial intelligence.

Brain‐inspired Multimodal Synaptic Memory via Mechano‐photonic Plasticized Asymmetric Ferroelectric Heterostructure

Gong,

Wei,

Wang

et al. 2024

Soft Multimodal Sensors with Decoupled Multimodality and Minimal Wiring for Wearable Systems

Lee,

Bae

2024

Soft multimodal sensors represent a promising approach for applications in wearable systems and skin‐adhesive devices, benefiting from their flexibility and body compatibility. However, the complexity of sensor wiring design poses challenges while employing multimodal decoupling. Although recent studies have applied various methods, such as adjusting the electrical properties of materials, these methods encounter limitations in signal decoupling when multichannel measurements are implemented. In this study, a signal measurement method utilizing frequency response analysis is developed using a multi‐band band‐stop filter (MBBSF) for multiple multimodal sensors. This approach enables the decoupling of different types of sensors and allows for the simultaneous collection of sensor data through a two‐wire connection. Consequently, it facilitates the concurrent and independent real‐time assessment of strain and force in each sensor. A sensor glove is developed incorporating multiple multimodal sensors with a two‐wire connection to measure grip posture and force. This glove is used effectively to classify unknown objects, thereby demonstrating its practical utility. This practical application provides a promising solution to the complex wiring challenges commonly encountered in multi‐modal sensor wearable systems.

Realizing Bidirectional Photocurrent in Monolithic Dual‐Mode Device for Neuromorphic Vision and Logically‐Encrypted Transmission

Jiang,

Zhao,

Bian

et al. 2024

Due to significant response contradictions, unidirectional carrier transmission of typical semiconductor p‐n junctions limits integrated sensors and artificial synapses in a monolithic device. In this work, a bipolar p‐n junction designed by employing the hydrogel/p‐GaN local contact interface with p‐GaN/(In,Ga)N heterojunction, demonstrating the bidirectional photocurrent and sensor/artificial synapse dual‐mode device successfully. After modifying Au nanoparticles, the negative (positive) photocurrent is increased by 900% (300%) under 365 nm (520 nm) light to achieve a more balanced bipolar carrier dynamic. Such a regulation of photocurrent is found to be attributed to the promotion of hydrogen evolution reaction (HER) at the hydrogel/Au/p‐GaN interface. Thus, the device achieves the ultrahigh paired‐pulse facilitation (PPF) index of 243% under self‐powered condition. Moreover, the implementation of plasticity from short‐term to long‐term demonstrates its adaptability in neural morphology visual recognition. Beyond independent working mode, the function of five classic logic gates is achieved under three‐terminal operation. Finally, an encrypted wireless communication system using dual‐channel light signals demonstrates the extensive application potential of the monolithic device. Therefore, this work presents a viable construction blueprint to meet the demands of next‐generation all‐in‐one optoelectronics for intricate application scenarios.