The contradiction between the high number of visually handicapped people and the scarcity of guide dogs has stimulated the demand for electronic guide dogs (EGDs). Here, we demonstrate an EGD by leveraging piezoresistors on a MoS₂/Ge heterostructure for simultaneous pressure-sensing and optical-sensing functions. The device has excellent gating capability and exhibits large positive and negative photoresponses under visible (532 nm, 182 A/W) and infrared (1550 nm, 37 A/W) illumination. These characteristics allow the device to efficiently classify different obstacles at all times of day using pressure and light signals. The device reaches nearly 100% accuracy after 48 training sessions when used to classify frequent scenes. The device adopts passive and active detection modes during the day and night, respectively, which improves the battery life of the EGD. This work provides a significant reference for the future design of EGDs, which may help a greater number of visually impaired people by reducing the cost of such devices.

A visual and tactile multisensory integrated system is essential for human walking due to the demand for real-time interactions between perception and action. Here, a piezoresistor and MoS₂ field effect transistor are combined to construct an artificial integration nervous system to simulate perception and synaptic plasticity. The key characteristics of synaptic plasticity are successfully demonstrated by individual pressure signals, individual optical signals, and the synergy of optical and pressure signals, which are based on the electron trapping–detrapping mechanism at the MoS₂/SiO₂ interface. We demonstrate that perception under synergy is stronger than perception under optical or pressure signal alone, which is similar to a biological system. Moreover, various distinguishable motion scenarios (combination of the following conditions: external lighting environment of day or night, flat or rough road, and movement state of walking or running) are simulated and verified by adjusting the amplitude and frequency of the optical and pressure signals.

The properties of photodetectors based on two-dimensional materials can be significantly enhanced by avalanche effect. However, a high avalanche breakdown voltage is needed to reach impact ionization, which leads to high power consumption. Here, we report the unique features of a low-voltage avalanche phototransistor formed by an in-plane WSe₂ field effect transistor (FET) with an out-of-plane WSe₂/WS₂ P–N heterojunction (HJ FET). The avalanche breakdown voltage in the device can be decreased from −31 to −8.5 V when compared with that in WSe₂ FET. The inherent mechanism is mainly related to the redistributed electric field in the WSe₂ channel after the formation of the out-of-plane P–N heterojunction. When the bias voltage is −16.5 V, the photoresponsivity in the HJ FET is enhanced from 1.5 to 135 A/W, which is significantly higher than that in the WSe₂ FET because of the obvious reduction of the avalanche breakdown voltage. Moreover, HJ FET shows a higher responsivity than WSe₂ FET in the range of 400–1,100 nm under low bias voltage. This phenomenon is caused by accelerating electron–hole spatial separation in the heterojunction. These results indicate that the use of an WSe₂ FET with an out-of-plane WSe₂/WS₂ heterojunction is ideal for high-performance photodetectors with low power consumption.