Flexible Waterproof Piezoresistive Pressure Sensors with Wide Linear Working Range Based on Conductive Fabrics

Developing flexible sensors with high working performance holds intense interest for diverse applications in leveraging the Internet-of-things(IoT)infrastructures.For flexible piezoresistive sensors,traditionally most efforts are focused on tailoring the sensing materials to enhance the contact resistance variation for improving the sensitivity and working range,and it,however,remains challenging to simultaneously achieve flexible sensor with a linear working range over a high-pressure region(>100 kPa)and keep a reliable sensitivity.Herein,we devised a laserengraved silver-coated fabric as"soft"sensor electrode material to markedly advance the flexible sensor's linear working range to a level of 800 kPa with a high sensitivity of 6.4 kPa^-1 yet a fast response time of only 4 ms as well as long-time durability,which was rarely reported before.The integrated sensor successfully routed the wireless signal of pulse rate to the portable smartphone,further demonstrating its potential as a reliable electronic.Along with the rationally building the electrode instead of merely focusing on sensing materials capable of significantly improving the sensor's performance,we expect that this design concept and sensor system could potentially pave the way for developing more advanced wearable electronics in the future.

High-performance magnesium ion asymmetric Ppy@FeOOH//Mn3O4 micro-supercapacitor

Micro-supercapacitors(MSCs)are attractive electrochemical energy storage devices owing to their high power density and extended cycling stability.However,relatively low areal energy density still hinders their practical applications.Here,an asymmetric Mg ion MSC with promising high energy density is fabricated.Firstly,indium tin oxide(ITO)NWs were synthesized by chemical vapor deposition as the excellent current collector.Subsequently,nanostructured Mn_(3)O_(4)and Ppy@FeOOH were deposited on the laser-engraved interdigital structure ITO NWs electrodes as the positive and negative electrodes,respectively.Beneficial from the hierarchical micro-nano structures of active materials,high conductive electron transport pathways,and charge-balanced asymmetric electrodes,the obtained MSC possesses a high potential window of 2.2 V and a high areal capacitance of 107.3 mF cm^(-2)at 0.2 mA cm^(-2).The insitu XRD,VSM,and ex-situ XPS results reveal that the primary energy storage mechanism of Mg ions in negative FeOOH electrode is Mg ions de-/intercalation and phase transition reaction of FeOOH.Furthermore,the MSC exhibits a high specific energy density of 71.18μWh cm^(-2)at a power density of 0.22 mWh cm^(-2)and capacitance retention of 85%after 5000 cycles with unvaried Coulombic efficiency.These results suggest promising applications of our MSC in miniaturized energy storage devices.

Regulation of cell locomotion by nanosecond-laser-induced hydroxyapatite patterning

Hydroxyapatite,an essential mineral in human bones composed mainly of calcium and phosphorus,is widely used to coat bone graft and implant surfaces for enhanced biocompatibility and bone formation.For a strong implant-bone bond,the bone-forming cells must not only adhere to the implant surface but also move to the surface requiring bone formation.However,strong adhesion tends to inhibit cell migration on the surface of hydroxyapatite.Herein,a cell migration highway pattern that can promote cell migration was prepared using a nanosecond laser on hydroxyapatite coating.The developed surface promoted bone-forming cell movement compared with the unpatterned hydroxyapatite surface,and the cell adhesion and movement speed could be controlled by adjusting the pattern width.Live-cell microscopy,cell tracking,and serum protein analysis revealed the fundamental principle of this phenomenon.These findings are applicable to hydroxyapatite-coated biomaterials and can be implemented easily by laser patterning without complicated processes.The cell migration highway can promote and control cell movement while maintaining the existing advantages of hydroxyapatite coatings.Furthermore,it can be applied to the surface treatment of not only implant materials directly bonded to bone but also various implanted biomaterials implanted that require cell movement control.

A time sequential microfluid sensor with Tesla valve channels

The concentration of biomarkers in sweat can be used to evaluate human health,making efficient sweat sensing a focus of research.While flow channel design is often used to detect sweat velocity,it is rarely incorporated into the sensing of biomarkers,limiting the richness of sensing results.In this study,we report a time sequential sensing scheme for uric acid in sweat through a sequential design of Tesla valve channels.Graphene electrodes for detecting uric acid and directional Tesla valve flow channels were fabricated using laser engraving technology to realize time sequential sensing.The performance of the channels was verified through simulation.The time sequential detection of uric acid concentration in sweat can help researchers improve the establishment of human health management systems through flexible wearable devices.

Graphene meta-aerogels:When sculpture aesthetic meets 1D/2D composite materials

The engraving technique has grown in parallel with our human civilization,along with the targeted materials evolving from stone and metals to wood.Benefiting from the blossom of nanotechnology,the bulky nicking tools have downsized themselves to a micro-/nanoscale,such as laser beams,and the materials have been extended from traditional hard ones to soft functional nanomaterials.When ancient sculpture art meets modern advanced micro-/nano fabrication techniques and low-dimensional materials,impossible materials are born,which will redefine the functional scope of well-developed materials.Recently,a team from Tsinghua University reported such fascinating materials,graphene-based meta-aerogels,that process excellent elasticity,ultralight specific weight(down to 0.1 mg·cm^(−3)),and superwide Poisson's ratio range(−0.95<v_(peak)<1.64)via facile and fast laser-engraving technique.