Libo Gao

• PhD in Nanomanufacturing and Flexible electronics
• Professor (Associate) at Xiamen University

The rapid development of flexible sensor technology has made flexible sensor arrays a key research area in various applications due to their exceptional flexibility, wearability, and large-area-sensing capabilities. These arrays can precisely monitor physical parameters like pressure and strain in complex environments, making them highly beneficial...

The alarming prevalence and mortality rates associated with cardiovascular diseases have emphasized the urgency for innovative detection solutions. Traditional methods, often costly, bulky, and prone to subjectivity, fall short of meeting the need for daily monitoring. Digital and portable wearable monitoring devices have emerged as a promising res...

Flexible pressure sensors hold considerable promise for applications in marine pressure detection due to their highly conformal capability to accommodate the nonplanar surface. However, fabricating a flexible pressure sensor with heightened sensitivity under substantial hydrostatic pressure in oceanic environments presents an enormous challenge due...

Reliable, non‐invasive, continuous monitoring of pulse and blood pressure is essential for the prevention and diagnosis of cardiovascular diseases. However, the pulse wave varies drastically among individuals or even over time in the same individual, presenting significant challenges for the existing pulse sensing systems. Inspired by pulse diagnos...

Flexible temperature sensors have diverse applications and a great potential in the field of temperature monitoring, including healthcare, smart homes and the automotive industry. However, the current flexible temperature sensor preparation generally suffers from process complexity, which limits its development and application. In this paper, a nic...

Real-time physiological information monitoring can predict and prevent disease, or improve treatment by early diagnosis. A comprehensive and continuous monitoring of human health requires highly integrated wearable and comfortable sensing devices. To address this need, we propose a low-cost electronic fabric-enabled multifunctional flexible sensing...

Metaverse as a comprehensive integration of multiple digital technologies of the new generation, enables human beings to bring unprecedented immersive experiences with the support of virtual reality, augmented reality, blockchain, digital twin, Artificial Intelligence, haptic internet of things (IoT), and human–computer interaction. In view of the...

With the modernization of traditional Chinese medicine (TCM), creating devices to digitalize aspects of pulse diagnosis has proved to be challenging. The currently available pulse detection devices usually rely on external pressure devices, which are either bulky or poorly integrated, hindering their practical application. In this work, we propose...

Biomimetics is an indispensable discipline in modern sensing technology and has been the source of inspiration for many significant inventions. Building upon the foundation of MEMS cantilever beam accelerometers, this paper combines biomimetic theory to propose an integrated MEMS acoustic-vibratory sensing structure that imitates the ear bones of s...

Exploded diagram of the sensor array and its core mechanism. The three-dimensional hierarchical insulation is realized at the intersection of sensor rows and columns, and the minimum port output of the interdigital array sensor array is realized.

The emerging field of flexible tactile sensing systems, equipped with multi-physical tactile sensing capabilities, holds vast potential across diverse domains such as medical monitoring, robotics, and human–computer interaction. In response to the prevailing challenges associated with the limited integration and sensitivity of flexible tactile sens...

Flexible conformal-enabled antennas have great potential for various developable surface-built unmanned aerial vehicles (UAVs) due to their superior mechanical compliance as well as maintaining excellent electromagnetic features. However, it remains a challenge that the antenna holds bending and thermal insensitivity to negligibly shift resonant fr...

Accurate data acquisition from flexible sensors placed on deformable 3D freeform surfaces is of critical importance for many applications, such as wearable electronics, human‐machine interfaces, and soft robotics. However, the mechanical coupling between the sensor and the deformable subject surface to bending and stretching deformations can signif...

This work prepared a reduced graphene oxide coated wood sponge for high-property pressure and temperature multifunctional sensors which can realize high sensitivity, large pressure range, and low detection limit.

Flexible three-dimensional (3D) force sensors have been extensively investigated in the field of robotics due to their ability to provide feedback information from multiple directions. However, the development of flexible 3D force sensors with high sensitivity and decoupling capabilities remains a significant challenge, hindering the ability of rob...

Post-surgical treatments of the human throat often require continuous monitoring of diverse vital and muscle activities. However, wireless, continuous monitoring and analysis of these activities directly from the throat skin have not been developed. Here, we report the design and validation of a fully integrated standalone stretchable device platfo...

Quartz resonant pressure sensors have shown tremendous potential in aerospace, biomedical, and traditional industries. Nevertheless, the complexity of assembly poses a significant challenge to their cost, while high-pressure sensors bring additional limitations. To overcome these challenges, this study introduces a novel quartz resonant pressure se...

Wireless passive sensors based on inductor-capacitor (LC) circuits have been an area of intense research in wearable electronics because of their battery-free and wirelessly connected operation. However, significant challenges remain in achieving high sensitivity and long-range performance for such device. In this study, we present a bilayer coils...

Flexible wearable sensors have garnered significant interest in the fields of human-computer interaction, materials science, and biomedicine [...]

In recent years, flexible pressure sensing arrays applied in medical monitoring, human-machine interaction, and the Internet of Things have received a lot of attention for their excellent performance. Epidermal sensing arrays can enable the sensing of physiological information, pressure, and other information such as haptics, providing new avenues...

Recently, flexible iontronic pressure sensors (FIPSs) with higher sensitivities and wider sensing ranges than conventional capacitive sensors have been widely investigated. Due to the difficulty of fabricating the nanostructures that are commonly used on electrodes and ionic layers by screen printing techniques, strategies for fabricating such devi...

Post-surgical treatments of the human throat and various diseases often require continuous monitoring of diverse vital and muscle activities. However, wireless, continuous monitoring and analysis of these activities directly from the (throat) skin still remain elusive. Here, we report the design and validation of a fully integrated standalone stret...

To realize a hyperconnected smart society with high productivity, advances in flexible sensing technology are highly needed. Nowadays, flexible sensing technology has witnessed improvements in both the hardware performances of sensor devices and the data processing capabilities of the device's software. Significant research efforts have been devote...

Soft piezocapacitive sensor, owing to its simple assembly and low power consumption, draws intensive interests for physiological monitoring. However, crosstalk between proximity sensing units and limited mechanically stretching suppressed its practical application for conventional capacitive sensor array. Here we report a stretchable iontronic pres...

Flexible iontronic pressure sensors (FIPS) with high sensitivity and wide sensing range compared to conventional capacitive sensors have recently been widely investigated. However, mainly due to the difficulty of fabricating nanostructures commonly used on electrodes or ionic layers by screen printing techniques, strategies to fabricate such device...

The combination of flexible textiles and novel 2D conductive materials opens up new possibilities for wearable intelligent sensors, which are particularly prominent in human-computer interaction, smart e-textile, and health monitoring....

As a wireless basic unit, flexible antennas hold a wide range of applications in wearable electronics, soft robotics, and Things of Internet (IoT). However, most of the current flexible antennas are encapsulated by silicone elastomers with poor gas permeability, which severely hinders the evaporation of skin moisture and sweat. In addition, convent...

Radial artery pulse pressure contains abundant cardiovascular physiological and pathological information, which plays an important role in clinical diagnosis of traditional Chinese medical science. However, many photoelectric sensors and pressure sensors will lose a large number of waveform features in monitoring pulse, which will make it difficult...

Flexible piezoelectric sensors hold great promising for applications in electronic skin (E-skin), wearable devices, and biomedical devices. However, it is still challenging to apply flexible piezoelectric sensors to respiratory health monitoring which requires an extremely low detection limit. To address this challenge, a flexible bionic piezoelect...

Flexible pressure sensors hold great potential for applications in human–machine interaction and flexible robotics, but the balance of their sensitivity and sensing range remains a challenge. Here, we proposed a flexible piezoresistive pressure sensor based on poly (3,4-ethylenedioxythiophene):poly(styrene sulfonic acid) (PEDOT: PSS) and cross inte...

Flexible sensors with proximity and tactile sensing have attracted great interest in electronic skins (E-skin), human-machine interfaces (HMI), and soft robotics. However, it remains challenging to have both proximity and haptic sensing ability in one flexible device, yet enable wireless sensing. Here, based on the edge electric field and piezo-cap...

The high demand for flexible force sensors with both strain and pressure sensing has attracted considerable attention for various application scenarios, such as electronic skins and smart prostheses. However, successful application of these sensors in real-world is challenging because the performance of the sensors can be severely degraded under ap...

Flexible pressure sensors play an important role in flexible robotics, human-machine interaction (HMI), and human physiological information. However, most of the reported flexible pressure sensors suffer from a highly nonlinear response and a significant decrease in sensitivity at high pressures. Herein, we propose a flexible novel iontronic pressu...

Nature materials usually possess unique hierarchical structures, like spongy bone, tendon and bamboo, and often exhibit remarkable mechanical properties. In this paper, inspired by the structural hierarchy of biological materials, the novel configuration design of unit cell with inner hierarchy was developed. The new lattice configuration takes adv...

Highlights The iontronic pressure sensor achieved an ultrahigh sensitivity ( S min > 200 kPa ⁻¹ , S max > 45,000 kPa ⁻¹ ). The iontronic pressure sensor exhibited a broad sensing range of over 1.4 MPa. Pseudocapacitive iontronic pressure sensor using MXene was proposed. ABSTRACT Flexible pressure sensors are unprecedentedly studied on monitoring h...

Monitoring biophysical signals such as body or organ movements and other physical phenomena is necessary for patient rehabilitation. However, stretchable flexible pressure sensors with high sensitivity and a broad range that can meet these requirements are still lacking. Herein, we successfully monitored various vital biophysical features and imple...

Inkjet printing-based 2D materials for flexible electronics have aroused much interest due to their highly low-cost customization and manufacturing resolution. However, there is a lack of investigation and essential understanding of the surface adhesion affected by the printing parameters at the atomic scale. Herein, we conducted a systematic molec...

The significant advancement in 2D materials fabrications has ushered a paradigm shift in material chemistry, which in turn has greatly influenced the manufacturing industries, in terms of products offered to the global community. The development of smart flexible electronics is one of such advancements, with remarkable potentials when intelligently...

Flexible tactile sensors (FTS), which have been extensively used in force sensing devices, are gaining tremendous attentions in various application fields, such as robots, electronic skin (E-Skin), human-machine interaction (HMI), and many other rapidly developing frontier technologies. However, fabricating FTS achieving both high sensitivity and b...

The pervasive renewable vibration energy has been considered as a promising alternative to electrochemical energy of batteries for powering wireless sensors and wearable electronics, but its efficient harvesting is still an unsolved problem. To tackle this issue, this paper presents an innovative mechanical modulation mechanism, which we name ‘cant...

Significant efforts have been devoted to enhancing the sensitivity and working range of flexible pressure sensors to improve the precise measurement of subtle variations in pressure over a wide detection spectrum. However, achieving sensitivities exceeding 1000 kPa−1 while maintaining a pressure working range over 100 kPa is still challenging becau...

The rapid advancement in CAD and 3D printing technology have brought the rise of mechanical metamaterials which inspired from nature and have optimized microstructural features to exhibit superior mechanical properties over conventional materials for various structural applications. Here, by adopting dual-phase strengthening mechanism in crystallog...

Insufficient mechanical properties of stereolithography (SLA)-printed architected polymer metamaterial limits its wide applications such as in the areas of biomedicine and aerospace. One effective solution is to reinforce the structures with micro- or nano- fibers/particles, but their interfaces are critical for the reinforcement. In this work, a c...

The past 2 decades have witnessed the explosion of research on two-dimensional (2D) materials, where notable efforts have been made in the synthesis and design of a wide spectrum of applications. To understand their mechanical properties and responses triggered by deformation, the prerequisites for reliable applications under realistic service cond...

Stretchable and flexible electronics conformal to human skin or implanted into biological tissues has attracted considerable interest for emerging applications in health monitoring and medical treatment. Although various stretchable materials and structures have been designed and manufactured, most are limited to two-dimensional (2D) layouts for in...

This paper presents an inverse computation method for measuring the anisotropic plasticity properties of materials using indentation. The advantage of this method is that, material plastic parameters are treated as stochastic variables with statistical distributions, of which potential uncertainties in numerical optimization process are considered....

To explore the full potential of graphene, a two-dimensional (2D) nanomaterial with outstanding physical and mechanical properties, for macroscopic applications, an essential prerequisite is to realize controllable assembly of graphene mono/multi-layers into engineered three-dimensional (3D) micro/macro-architectures with well-defined microstructur...

The laser-engraved method was introduced to fabricate the electrode for the sensor.The sensor showed a wide linear working range, superior sensitivity, and fast response time and also exhibited excellent viability in a wet situation.Wireless integrated network sensors successfully monitored the health states. The laser-engraved method was introduce...

Monolayer hexagonal boron nitride can serve in optoelectronics or as a dielectric in graphene and other two-dimensional (2D) electronics due to its ultra-wide band gap. As there is no center of symmetry, monolayer hexagonal boron nitride (h-BN) also shows piezoelectricity. However, these applications require h-BN to sustain large uniform elastic de...

In nano-electronic field, cold welding is a simple novel method to join ultrathin noble metal nanowires (NWs) without introducing extra energy and defects. In previous works, it always occurred between ultrathin noble metal NWs, tensile fracture parts of a single NW, or a NW formation from nanoparticles. However, some external force is still needed...

Flexible transparent conductive films are indispensable for nowadays wearable electronic devices with various applications. However, existing solutions such as ITO and metal mesh were limited by their poor intrinsic stretching ability. In this work, we designed and fabricated silver nanowires (AgNWs) on graphene hybrid films for enhanced mechanical...

Compared with conventional prosthesis with homogenous structures, functionally graded lattice prosthesis with optimized stress distribution have both mechanical and biological advantages, thus better adapt to the gradient nature of host bones. In this study, we focus on design and fabricating mandibular prosthesis based on polymer stereolithography...

The sp2 nature of graphene endows the hexagonal lattice with very high theoretical stiffness, strength and resilience, all well-documented. However, the ultimate stretchability of graphene has not yet been demonstrated due to the difficulties in experimental design. Here, directly performing in situ tensile tests in a scanning electron microscope a...

Atomic simulations give a good explanation of the changes in the physical properties of a material. In this work, the tension behaviors of nanopolycrystalline Cu–Ta alloys are investigated through molecular dynamics (MD) simulations, and the influences of several important factors on the mechanical properties of the materials are studied. Firstly,...

Recently, gold nanoribbons (Au NRBs) with hexagonal (4H) phase have emerged as a new kind of ultrathin Au nanostructure with unusual metastable crystal phase, which could possess unique physiochemical properties and various promising applications. However, its geometric structure and phase stability under realistic service conditions, like Joule he...

Flexible sensor with superior sensitivity and widened working range is urgently demanded to cater for the rapid progress of wearable electronics and mechnosensational human-machine interfaces. However, the manufacturing of the wearable sensor with promising sensitivity in a broad working range is a challenge for the soft property of the sensing mat...

The excellent mechanical properties of single- and few-layer graphene have been well-quantified and evidenced by computational methods and local indentation measurements. However, there are less experimental reports on the in-plane mechanical properties of multilayer graphene sheets, despite many practical applications in flexible electronic and en...

The rise of one-dimensional micro/nanomaterials requires comprehensive understanding on their mechanical properties. Recently, MEMS (micro-electromechanical system)-type devices become an efficient tool for characterizing the mechanical behavior of 1D micro/nanomaterials under high resolution electron microscope or optical microscope. However, exis...

Developing a generalized route to effectively fabricate periodic mechanically flexible graphene aerogels across several size orders and whole structural integrity on a large scale for flexible electronics is still a challenge. Herein, inspired by bamboo's natural hierarchical structure, a general method is developed to effectively fabricate biomime...

The lipid bilayer membrane is a major component of cells and intracellular membranes in vivo, and plays an indispensable role in organisms. Currently in the medical field, lipid bilayer membranes are used as devices for targeted delivery of proteins, nucleic acids and drugs in the treatment of a variety of diseases. Based on coarse-grained molecula...

A highly sensitive portable piezoresistive sensor with a fast response-time in an extended linear working range is urgently needed to meet the rapid development of the artificial intelligence (AI), interactive human–machine interface and ubiquitous flexible-electronics. However, it is a challenge to rationally couple these figure-of-merits (sensiti...

A molecular dynamics (MD) study is carried out to reveal the phenomenon about the normal and explosive boiling of ultra-thin liquid argon film absorbed on MoS2 surface with different wetting conditions. The three-phase molecular system is composed of a solid MoS2 wall, a liquid argon film and a vapour argon region. Initially, the three-phase simula...

It is known that metamaterials with negative Poisson’s ratio (NPR) can be designed to possess negative thermal expansion (NTE) property. However, it is uncommon to use NTE structures to obtain NPR behavior. In this paper, based on a typical NTE unit structure, two novel meta-structures with auxetic behavior are proposed, which are demonstrated by t...

Flexible fiber-shaped supercapacitors (FFSSs) hold promising prospect to meet the increasingly high requirements of the wearable electronics. However, today it remains a great challenge to construct advanced supercapacitor with high areal capacity and favorable rate capability to achieve superior energy density in facile route is a great challenge....

In the past decade, mechanical metamaterials have garnered increasing attention owing to its novel design principles which combine the concept of hierarchical architecture with material size effects at micro/nanoscale. This strategy is demonstrated to exhibit superior mechanical performance that allows us to colonize unexplored regions in the mater...

Wearable triboelectric nanogenerators (TENGs) have attracted interest in recent years, which demand highly flexible, scalable, and low-cost features. Here, we report an ultra-flexible, large-scale and textile-based TENG (T-TENG) for scavenging human motion energy. The triboelectric layer was derived from the polydimethylsiloxane (PDMS) film with a...

An equiatomic CoCrFeMnNi high-entropy alloy (HEA) thin film coating has been successfully developed by high-vacuum Radio Frequency (RF) magnetron sputtering. The deposition of a smooth and homogenous thin film with uniformly distributed equiaxed nanograins (grain size ~ 10 nm) was achieved through this technique. The thin film coating exhibits a hi...

Graphene-bridged Multifunctional Flexible Fiber Supercapacitor with High Energy Density

Portable fiber supercapacitors with high energy storage capacity are in great demand to cater for the rapid development of flexible and deformable electronic devices. Hence, we employed a 3D cellular copper foam (CF) combined with the graphene sheets (GSs) as the support matrix to bridge the active material with nickel fiber (NF) current collector,...

The TiSiN/Ag multilayer coatings with fixed TiSiN layer thickness and different individual Ag layer thicknesses were prepared by arc ion plating. Quantification of mechanical response of TiSiN/Ag multilayer coatings through uniaxial micropillar compression tests was carried out to identify the elastic modulus, fracture strength, deformation and fai...

Silver (Ag) nanowires have great potential to be used in the flexible electronics industry for their applications in flexible, transparent conductors due to high conductivity and light reflectivity. Those applications always involve mechanical loading and deformations, which requires an in-depth understanding of their mechanical behavior and perfor...

Mechanical metamaterials such as microlattices are an emerging kind of new materials that utilize the combination of structural enhancement effect by geometrical modification and the intrinsic properties of its material constituents. Prior studies have reported the mechanical properties of ceramic or metal-coated composite lattices. However, the sc...

Recently solid asymmetric supercapacitor (ASC) has been deemed as an emerging portable power storage or backup device for harvesting natural resources. Here we rationally engineered a hierarchical, mechanically stable heterostructured FeCo@NiCo layered double hydroxide (LDH) with superior capacitive performance by a simple two-step electrodepositio...

The HEA-CoCrFeNiAl0.3 thin film in this study has been successfully developed by radio frequency (RF) magnetron sputtering to meet the increasing demand in engineering applications. Its microstructure and surface profile were investigated accordingly. The as-synthesized HEA film was found to have a homogeneous element distribution and ultra-smooth...