| One of the major challenges in modern agricultural development is how to minimize crop losses caused by biotic and abiotic stressors,while enhancing resource efficiency and reducing environmental pollution.To meet the growing global food demand,interdisciplinary approaches combining plant science and engineering are required for sustainable agricultural production.However,current plant monitoring techniques suffer from various limitations such as discontinuity,low sensitivity,susceptibility to interference,and difficulty in achieving non-destructive in-situ sensing.Therefore,there is an urgent need to develop new sensing methods and technologies to enable real-time monitoring,tracking,and prediction of plant microenvironments and related stressors.In this research,we developed an additive-free MXene aqueous ink-based room-temperature printing technology for fabricating plant wearable wireless electronics,which enables integrated printing of wireless,power,and sensing functional modules.In addition,we studied the formation mechanism of highly conductive printed circuits and explored the hybrid energy harvesting mechanism of the self-powered wireless charging modules.By integrating multiple printed modules,we constructed a plant wearable battery-free wireless sensing system that enables continuous,non-destructive,and in-situ monitoring of the plant microenvironment and stressors.The modular design of the plant wearable sensing system has great potential for further compatibility of different functional modules.This work provides new ideas and technical approaches for the development of next-generation micro-nano plant sensing devices and systems.The main research contents and results are as follows:（1）In order to overcome the challenge that rigid sensors are difficult to effectively fit on irregular plant leaf surfaces,while simplifying the design and fabrication process of plant wearable sensors,this work proposed a room-temperature printing method for plant wearable sensors enabled by MXene aqueous ink.By optimizing the ink configuration process,the additive-free MXene aqueous ink has high-concentration（～60 mg/m L）,high monolayer ratio（>90%）,and narrow flake size distribution.High viscosity and high elastic modulus allow MXene ink to retain its shape after printing and dry quickly,eliminating the need for cumbersome post-processing steps such as high-temperature annealing.MXene ink-enabled extrusion printing allows for high-precision printing at room temperature,resulting in clear lines with sharp edges that can achieve an ultra-narrow line spacing of 3μm and high uniformity of less than 0.43%.This method allows for conformal printing on irregular surfaces,making it a versatile choice for printing on a variety of substrates.The printed MXene film is flexible and stable,with a smooth surface and a dense internal structure,and has a maximum electrical conductivity of 6900 S cm-1.This chapter lays the foundation for the subsequent design and development of plant wearable devices and systems.（2）In order to enable wireless wireless communication and power transfer functions of wearable plant devices,two types of plant wearable wireless devices have been designed and developed.By utilizing additive-free MXene aqueous ink,different radio frequency（RF）antennas can be fabricated at room temperature on different flexible substrates to produce wireless devices.Combined with near field communication（NFC）technology,the NFC coil antenna was designed and printed,allowing stable access at a frequency of 13.56 MHz and enabling wireless data transmission and energy transfer simultaneously.The developed NFC tags were highly flexible,which can be used for electronic recording and plant information identification.In addition,a dipole antenna with an operating frequency of 920 MHz was printed in combination with radio frequency identification（RFID）technology,and flexible RFID temperature tags were fabricated to enable long-distance plant leaf temperature monitoring.This chapter lays the technical foundation for wireless communication in the subsequent construction of battery-free wireless plant wearable systems.（3）In order to ensure the stable power supply of plant wearable devices and achieve self-powered sensing and battery-free continuous operation,a hybrid energy harvesting device for plant wearables was developed that supports both wireless charging and triboelectric nanogenerator（TENG）functionality.The device consists of a hybrid energy module and a micro-supercapacitors（MSC）storage module,and is fabricated using MXene room-temperature printing technology.The device can wirelessly collect electricity through electromagnetic coupling,and output a stable 3 V voltage through diode rectification and capacitor filtering.In addition,the device can be used as a TENG with a power output of up to 0.67 m W.A new TENG working mode,namely the diode closed loop mode,was proposed by investigating the working principle of hybrid energy harvesting.Furthermore,the printed MSC has excellent electrochemical energy storage characteristics,with an area energy density and power density of up to 9.7μWh cm-2 and1.875 m W cm-2,respectively.This chapter lays the technical foundation for the power aspect of battery-free wireless plant wearable systems.（4）On the basis of the research conducted in the previous three chapters,a battery-free wireless plant wearable sensing system was constructed through integrated circuit design and multi-module integration printing.The system consists of four functional modules for sensing,energy storage,wireless communication,and control,which were manufactured using MXene aqueous ink at room temperature on the same flexible substrate.It enables wireless,in-situ sensing of temperature and humidity information in the microenvironment of plant growth,and supports data interaction with smartphones.The wireless module includes a printed NFC antenna responsible for wireless communication and energy harvesting.The sensing module includes fully-printed MXene sensors capable of stable and sensitive response to temperature and humidity.The energy module iincludes printed MSCs for storing wirelessly harvested power.The customized integrated circuit serves as the control module,responsible for data transmission and power management of the system.Experimental results confirm the feasibility of using this system for temperature and humidity monitoring in agricultural production,providing a scientific basis for precise temperature and irrigation control,which is of great significance for improving the growing environment of crops and ensuring quality and yield.In addition,the system holds great potential for upgrading and improvement,and can provide valuable reference and abundant technical reserves for the research and development of the next generation of plant micro-nano sensing platforms. |
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