Modern life continues to develop intelligently, as the latest achievement of the development of human society informationization, a large number of new technologies such as intelligent home, unmanned driving and virtual reality emerge successively. These technologies are no longer limited to the Internet in computers, mobile phones and other traditional intelligent devices to achieve interoperability, its applications can be extended to anything between objects, gradually forming a network of things covering the entire human life. The formation of such a large network of things, no doubt need intensive electronic devices to complete information sensing, transmission, processing, and so on, and how to continue to stabilize these electronic devices power supply is an important problem to be solved. Traditional line power supply is a big obstacle in solving this problem because there is no visible link between the objects in the natural state, so it is impractical for the electronic devices on these objects to be powered on line by circuit. The other method is the battery power, by equipping each electronic device with a storage device to realize the independent work of the device.
However, the shortage of battery power is also very obvious, that is, the battery will be depleted, in the case of electronic devices distributed intensively, remotely or even implanted, charging each battery will be very complicated work; second, electronic devices are moving towards miniaturization, lightweight, and batteries want to extend their battery life as much as possible, It inevitably increases the size and quality of its structure, which is contrary to the miniaturization and lightweight requirements of the whole system. Therefore, it is crucial to find a more suitable power supply route.
Piezoelectric nano-generators involve the conversion between mechanical energy and electrical energy, which can produce a piezoelectric signal when subjected to strain, which can be directly used as a sensor for detecting strain. Lee et al.  designed a strain sensor with ZnO as the piezoelectric layer, they used aluminum foil as the bottom electrode and a layer of polymer poly (PMMA) on the ZnO array layer to improve the stability of the device. This piezoelectric nano-generator thickness is only 16μm, with good flexibility, can be very good with the skin of the human body, so the skin can be weak deformation when the perception. Unlike the traditional strain sensor, the output signal of the device is produced by the nano-generator itself, and it does not require external power supply during the detection process, so the strain sensor can be completely driven by itself.
In addition to the need to reduce the thickness of the device, it is necessary to produce a sensor that is completely similar to human skin, with high scalability, biological friendliness, and large area of production. Lee and so on. By means of dry friction transfer, the two-axis ZnO nanorods are transferred to a flexible poly two-methyl siloxane (PDMS) film by a certain orientation, and a large area of highly ductile composite film is obtained. When the composite film receives tensile deformation, a piezoelectric signal is produced in the direction of the vertical film. The device is affixed to the joint of the finger, and with the movement of the finger can produce about 2 v/60 na electrical signals, showing its application potential in gesture recognition.
Human-computer interface is a bridge between the information exchange between people and hardware. In recent years, wearable human-computer interface has shown great potential in the field of personal mobile devices and IoT applications. The flexible and transparent wearable man-machine interface has become a focus of attention because of its wearing comfort and aesthetics. Lim et  reported a prototype of human-computer interaction interface based on polylactic acid piezoelectric material, carbon nanotubes and graphene composite heterogeneous layer structure. The device features ultra-thin and lightweight properties, and is extensible and transparent, and can be mounted on the human arm to accurately collect action information.