Publications

With the rapid development of computer vision, the application of computer vision to precision farming in animal husbandry is currently a hot research topic. Due to the scale of goose breeding continuing to expand, there are higher requirements for the efficiency of goose farming. To achieve precision animal husbandry and to avoid human influence on breeding, real-time automated monitoring methods have been used in this area. To be specific, on the basis of instance segmentation, the activities of individual geese are accurately detected, counted, and analyzed, which is effective for achieving traceability of the condition of the flock and reducing breeding costs. We trained QueryPNet, an advanced model, which could effectively perform segmentation and extraction of geese flock. Meanwhile, we proposed a novel neck module that improved the feature pyramid structure, making feature fusion more effective for both target detection and instance individual segmentation. At the same time, the number of model parameters was reduced by a rational design. This solution was tested on 639 datasets collected and labeled on specially created free-range goose farms. With the occlusion of vegetation and litters, the accuracies of the target detection and instance segmentation reached 0.963 (mAP@0.5) and 0.963 (mAP@0.5), respectively.

Triboelectric nanogenerator (TENG) is a newly invented technology that is effective using conventional organic materials with functionalized surfaces for converting mechanical energy into electricity, which is light weight, cost‐effective and easy scalable. Here, we present the first systematic analysis and comparison of EMIG and TENG from their working mechanisms, governing equations and output characteristics, aiming at establishing complementary applications of the two technologies for harvesting various mechanical energies. The equivalent transformation and conjunction operations of the two power sources for the external circuit are also explored, which provide appropriate evidences that the TENG can be considered as a current source with a large internal resistance, while the EMIG is equivalent to a voltage source with a small internal resistance. The theoretical comparison and experimental validations presented in this paper establish the basis of using the TENG as a new energy technology that could be parallel or possibly equivalently important as the EMIG for general power application at large‐scale. It opens a field of organic nanogenerator for chemists and materials scientists who can be first time using conventional organic materials for converting mechanical energy into electricity at a high efficiency.

We report the first self-powered electronic skin that consists of light-emitting diode (LED) and triboelectric nanogenerator (TENG) arrays that can be utilized for spatially mapping applied instantaneous-touch events and tracking the movement location of the target object by recording the electroluminescent signals of the LEDs without external power sources. The electret film-based TENG can deliver an open-circuit voltage of about −1070 V, a short-circuit current density of 10 mA/m2, and a power density of 288 mW/m2 on an external load of 100 MΩ. The LEDs can be turned on locally when the back surface of the active matrix is touched, and the intensity of the emitted light depends on the magnitude of the applied local pressure on the device. A constructed active matrix of the LED-TENG array (8 × 7 pixels) can achieve self-powered, visual, and high-resolution tactile sensing by recording the electroluminescent signals from all of the pixels, where the active size of each pixel can be decreased to 10 mm2. This work is a significant step forward in self-powered tactile-mapping visualization technology, with a wide range of potential applications in touchpad technology, personal signatures, smart wallpapers, robotics, and safety-monitoring devices.

Piezoelectric potential of a InN nanowire (NW) growing along [0110] can be positive, negative, and zero depending on the direction of the applied transverse force. By measuring the output voltage of a InN-NW-based nanogenerator, about 40% to 55% of output voltages are within the range of -1 and -20 mV, and 25% to 30% of output voltages would exceed -100 mV. Some output voltages could reach the magnitude of -1000 mV, showing its great potential for fabricating high-output nanogenerators.

Silicon-based photodetectors in photoelectric sensing applications are crucial. In the previous studies of the piezo-phototronic effect on performance modulation of Si/ZnO heterojunctions, the majority is based on a rigid silicon substrate and a ZnO one-dimensional nanostructure, causing incompatibility with advanced semiconductor processing technology as well as the limitation in the field of wearable application. Here, flexible p-Si/n-ZnO film heterojunction photodetectors have been constructed by sputtering ZnO films on chemically thinned Si substrates. Under 405 nm light illumination and at −0.5 V bias, the reverse photocurrent of the heterojunction under the −0.73‰ compression strain increased by 50.36% compared to that under a strain-free state, while the reverse photocurrent for the same device under 0.73‰ tensile strain decreased by 29.2% compared to that under the strain-free state. The introduction of a flexible silicon wafer realizes a bidirectional photocurrent response regulation, which lies in the fact that the strain-induced piezo-potential governs the local energy band structure at the heterojunction interface and, thus, influences the carrier transport in the heterojunction region. The COMSOL simulation results further verify the evolution of the energy band structure at the heterojunction interface at different strain states. This work provides a strategy to design silicon-based optoelectronic devices via the piezo-phototronic effect of a ZnO film.

A nanoscale semiconducting ZnO based biosensor with integrated microfluidics is designed, fabricated and tested to demonstrate the detection of streptavidin, a commonly used protein. Amperometric (I-t) measurement is utilized to detect the change of conductivity over time. By comparing with the control experiment, the specific binding event between biotin and streptavidin is detected. The data indicates a conductivity change by more than 20% after the protein hybridization. The second part of the papers presents a ZnO thin film based biosensor which is integated with a microfluidic system. Same experiment protocols are carried and similar change in I-t characteristics is observed. This is the first demonstration of real time biosensing with ZnO nanowires and thin films that are integrated with microfluidic systems. This can be further extended to fabricate bio-sensors which can potentially detect any protein in real time. Amperometric sensing results in a label-free detection system as it detects the protein hybridization events electrically. when integrated on the system-on-package (SOP) platform, this technology can lead to portable, reliable and cost effective biosensors with applications in many areas.

Abstract Contact electrification between two different materials is one of the oldest fields of study in solid-state physics. Here, we introduced an innovative system based on optical electric-field-induced second harmonic generation (EFI-SHG) technique that can directly monitor the dynamic performance of the contact electrification on the surface of polyimide film. After the contact, the EFI-SHG system visualized briefly three relaxations of the tribo-induced charges on the surface of a polyimide film, a fast relaxation within 3 min followed by two much slower relaxations, which were possibly related to different charge diffusion routes. The contact electrification under several special experimental conditions (wind, water and steam) was studied to demonstrate the high flexibility and material selectivity of the EFI-SHG. The EFI-SHG studies confirmed the motion of the water can remove the surface charge, while the appearance and the evaporation of a thin water layer cannot enhance the charge diffusion. We anticipate that this experimental technique will find a variety of applications in the field of contact electrification and the development of the recently invented triboelectric nano generator.