Wenbo Li

Nanoparticle Based Curve Arrays for Multirecognition Flexible Electronics.

Assembly of nanoparticles into controllable micro or nanocurve circuits by a feasible strategy is demonstrated. The curves, with various tortuosity morphologies, have tunable resistive strain sensitivity, which can be integrated into a multi-analysis flexible sensor. The curve-based sensor can run complicated facial expression recognition, and may contribute practical applications on auxiliary apparatus for skin micromotion manipulation for paraplegics.

Flexible Circuits and Soft Actuators by Printing Assembly of Graphene

An effective way to improve the electrical conductivity of printed graphene patterns was demonstrated by realizing the assembly of giant graphene oxide sheets during the printing process. The synergetic effect of printing-induced orientation and evaporation-induced interfacial assembly facilitated the formation of laminar-structured patterns. The resulting patterns after chemical reduction showed excellent electrical conductivity in printed graphene electronics. Because of their high conductivity, mechanical flexibility, and advantage in pattern design, printed graphene electrodes were applied in electrical-driven soft actuators, which can realize controllable deformation with low driving voltage. Such achievements will be of great significance for the development of graphene-based flexible and printed electronics.

Printing assembly and structural regulation of graphene towards three-dimensional flexible micro-supercapacitors

Flexible, high-performance miniature supercapacitors that offer reliable energy storage and output are desirable for use in portable and wearable electronics. Herein, we developed micro-supercapacitors with three-dimensional electrodes by printing assembly of graphene. By controlling the microstructures and macroscopic architectures of the graphene electrodes, superior electrochemical performance was achieved; especially, we demonstrated an advancement to address the limitation of areal capacitance. The unique three-dimensional graphene structure also provides this new class of micro-supercapacitors with exceptional mechanical flexibility. With these remarkable features, facile integration of the micro-supercapacitor array into flexible printed circuits was demonstrated. This printing assembly approach will pave the way to explore energy storage systems with diverse structures and extended functionalities.

Swarm Intelligence-Inspired Spontaneous Fabrication of Optimal Interconnect at the Micro/Nanoscale

A spontaneous process is demonstrated to assemble nanoparticles into an optimal interconnect, as natural systems spontaneously figure out the shortest path. The optimal interconnect leads to a 65.9% decrease in electromagnetic interference, a 17.1% decrease in delay, and a 24.5% decrease in energy-delay. It will be of great significance for interconnect fabrication of versatile electronic circuits.

Patterned photonic crystals for hiding information

Coding techniques are not only a popular strategy for information recording and communication, but also an efficient strategy for information protection. Many species in nature, such as chameleons and peacocks, demonstrate brilliant colourful appearances for camouflage, courtship or communication. The unique optical property that originates from the interaction of light with the periodic nanostructures on their surfaces, known as photonic crystals (PCs), provides an attractive candidate for coding and anti-counterfeiting. Here we present a prototype design for hiding information in photonic crystals by building a coding and encryption relationship between optical stopbands and information units. The hidden messages are protected by three different defense strategies: characteristic optical stopbands, algorithm encryption and angle-dependent encryption, which could dramatically improve the security level of the hidden information. In combination with the large coding capacity, inherent optical stability and robust fabrication process, this PC coding system has great potential for secure information storage and communication, anti-counterfeiting and massively parallelized sensors.

Printable Functional Chips Based on Nanoparticle Assembly

With facile manufacturability and modifiability, impressive nanoparticles (NPs) assembly applications were performed for functional patterned devices, which have attracted booming research attention due to their increasing applications in high-performance optical/electrical devices for sensing, electronics, displays, and catalysis. By virtue of easy and direct fabrication to desired patterns, high throughput, and low cost, NPs assembly printing is one of the most promising candidates for the manufacturing of functional micro-chips. In this review, an overview of the fabrications and applications of NPs patterned assembly by printing methods, including inkjet printing, lithography, imprinting, and extended printing techniques is presented. The assembly processes and mechanisms on various substrates with distinct wettabilities are deeply discussed and summarized. Via manipulating the droplet three phase contact line (TCL) pinning or slipping, the NPs contracted in ink are controllably assembled following the TCL, and generate novel functional chips and correlative integrate devices. Finally, the perspective of future developments and challenges is presented and widely exhibited.

Direct Writing of Patterned, Lead-Free Nanowire Aligned Flexible Piezoelectric Device

A high‐performance flexible piezoelectric nanogenerator (PNG) is fabricated by a direct writing method, which acquires both patterned piezoelectric structure and aligned piezoelectric nanowires simultaneously. The voltage output of the as‐prepared PNG is nearly 400% compared with that of the traditional spin‐coated device due to the effective utilization of stress. This facile printing approach provides an efficient strategy for significant improvement of the piezoresponse.

Gas/liquid interfacial manipulation by electrostatic inducing for nano-resolution printed circuits

A critical requirement for highly conductive metallic printing circuits is to obtain consecutive and high-resolution printed patterns. However, the aggregation or assembly of metallic nanocrystals in solution is usually random, which perplexes the consecutiveness and resolution of the printed circuits. In this study, we prepared consecutive nano-resolution circuits by gas/liquid interfacial manipulation. Consecutive gas/liquid interfaces were achieved by electrostatic inducing of a cationic metal ink using anionic surfactant onto the gas/liquid interface to form continuous patterns. Gas/liquid interfacial morphology was manipulated by gas/liquid/solid three phase contact line (TCL); Through controlling TCL sliding on different surfaces, submicron or nano-resolution circuits were fabricated, which showed excellent conductivity. This facile strategy showed significant potential for use in wearable electronics and high-resolution electronic circuits.

Bioinspired Synergy Sensor Chip of Photonic Crystals-Graphene Oxide for Multiamines Recognition

Benefiting from the integrated functions of cilia and glomeruli in the olfactory system, animals can discriminate various odors even in hostile environments. Inspired by this synergetic system of response and signal processing units, a sensor chip of graphene oxide (GO) and photonic crystals (PCs) is fabricated. The GO aerogel functions like the olfactory cilia, which effectively captures the analytes and generates abundant sensing signals for recognition; and the PCs act as the olfactory glomeruli, whose periodic structure enables selective enhancement of the fluorescent signals to realize further signal processing. Ten biogenic amines and seven drug amines are effectively discriminated. The integrated sensor strategy of response and signal manipulation units will promote enormous pursuits of rapid clinical diagnosis or intractable pathology analysis.

Printable Skin‐Driven Mechanoluminescence Devices via Nanodoped Matrix Modification

Mechanically driven light generation is an exciting and under-exploited phenomenon with a variety of possible practical applications. However, the current driving mode of mechanoluminescence (ML) devices needs strong stimuli. Here, a flexible sensitive ML device via nanodopant elasticity modulus modification is introduced. Rigid ZnS:M2+ (Mn/Cu)@Al2 O3 microparticles are dispersed into soft poly(dimethylsiloxane) (PDMS) film and printed out to form flexible devices. For various flexible and sensitive scenes, SiO2 nanoparticles are adopted to adjust the elasticity modulus of the PDMS matrix. The doped nanoparticles can concentrate stress to ZnS:M2+ (Mn/Cu)@Al2 O3 microparticles and achieve intense ML under weak stimuli of the moving skin. The printed nano-/microparticle-doped matrix film can achieve skin-driven ML, which can be adopted to present fetching augmented animations expressions. The printable ML film, amenable to large areas, low-cost manufacturing, and mechanical softness will be versatile on stress visualization, luminescent sensors, and open definitely new functional skin with novel augmented animations expressions, the photonic skin.