Patterned Nanoparticle Arrays Fabricated Using Liquid Film Rupture Self-Assembly.

Self-assembly is an important bottom-up fabrication approach based on accurate manipulation of solid-air-liquid interfaces to construct microscale structures using nanoscale materials. This approach plays a substantial role in the fabrication of microsensors, nanosensors, and actuators. Improving the controllability of self-assembly to realize large-scale regular micro/nano patterns is crucial for this approach's further development and wider applications. Herein, we propose a novel strategy for patterning nanoparticle arrays on soft substrates. This strategy is based on a unique process of liquid film rupture self-assembly that is convenient, precise, and cost-efficient for mass manufacturing. This approach involves two key steps. First, suspended liquid films comprising monolayer polystyrene (PS) spheres are realized via liquid-air interface self-assembly over prepatterned microstructures. Second, these suspended liquid films are ruptured in a controlled manner to induce the self-assembly of internal PS spheres around the morphological edges of the underlying microstructures. This nanoparticle array patterning method is comprehensively investigated in terms of the effect of the PS sphere size, morphological effect of the microstructured substrate, key factors influencing liquid film-rupture self-assembly, and optical transmittance of the fabricated samples. A maximum rupture rate of 95.4% was achieved with an optimized geometric and dimensional design. Compared with other nanoparticle-based self-assembly methods used to form patterned arrays, the proposed approach reduces the waste of nanoparticles substantially because all nanoparticles self-assemble around the prepatterned microstructures. More nanoparticles assemble to form prepatterned arrays, which could strengthen the nanoparticle array network without affecting the initial features of prepatterned microstructures.

Therapeutic strategies for retention of cranioplasty titanium mesh after mesh exposure.

BACKGROUND: Titanium mesh exposure after cranioplasty is a possible complication and is usually managed by mesh removal and flap transfer, but the advantages of the rigid prosthesis are then lost. This study aimed to present our experience with negative pressure wound therapy combined with soft tissue dilation for retaining the titanium mesh in patients with mesh exposure after cranioplasty. METHODS: This retrospective study included patients treated between 01/2016 and 05/2019 at the Jiangyin Hospital Affiliated to Southeast University School of Medicine. The wound was cleaned, and a cystic space was created for the tissue dilator, which was used with a self-designed negative pressure dressing. After the target dilation was achieved, the repair was conducted while retaining the titanium mesh. RESULTS: Eight patients were included (seven males and one female; 53.6 ± 8.8 (range, 43-65) years of age). The exposed mesh area ranged from 1 × 1 to 4 × 5.5 cm. The thinning scalp area around the exposed mesh ranged from 3.6 × 3.8 to 4 × 5.5 cm. Five patients had positive wound cultures and received sensitive antibiotics. The dilator embedding time was 20-28 days. The time of negative pressure wound therapy was 25-33 days. The hospital stay was 30-41 days. Primary wound healing was achieved in all eight patients. There were no signs of recurrence after 6-18 months of follow-up. The cranial CT scans were unremarkable. CONCLUSIONS: Negative pressure wound therapy combined with soft tissue dilation for exposed titanium mesh after cranioplasty might help retain the titanium mesh.

The Interface between Nanoenergy and Self-Powered Electronics.

In recent decades, nanogenerators based on several techniques such as triboelectric effects, piezoelectric effects, or other mechanisms have experienced great developments. The nanoenergy generated by nanogenerators is supposed to be used to overcome the problem of energy supply problems for portable electronics and to be applied to self-powered microsystems including sensors, actuators, integrated circuits, power sources, and so on. Researchers made many attempts to achieve a good solution and have performed many explorations. Massive efforts have been devoted to developing self-powered electronics, such as self-powered communication devices, self-powered human-machine interfaces, and self-powered sensors. To take full advantage of nanoenergy, we need to review the existing applications, look for similarities and differences, and then explore the ways of achieving various self-powered systems with better performance. In this review, the methods of applying nanogenerators in specific circumstances are studied. The applications of nanogenerators are classified into two categories, direct utilization and indirect utilization, according to whether a treatment process is needed. We expect to offer a line of thought for future research on self-powered electronics.

High-performance hybrid nanogenerator for self-powered wireless multi-sensing microsystems.

Wireless sensor network nodes are widely used in wearable devices, consumer electronics, and industrial electronics and are a crucial component of the Internet of Things (IoT). Recently, advanced power technology with sustainable energy supply and pollution-free characteristics has become a popular research focus. Herein, to realize an unattended and reliable power supply unit suitable for distributed IoT systems, we develop a high-performance triboelectric-electromagnetic hybrid nanogenerator (TEHNG) to harvest mechanical energy. The TEHNG achieves a high load power of 21.8 mW by implementing improvements of material optimization, configuration optimization and pyramid microstructure design. To realize a self-powered integrated microsystem, a power management module, energy storage module, sensing signal processing module, and microcontroller unit are integrated into the TEHNG. Furthermore, an all-in-one wireless multisensing microsystem comprising the TEHNG, the abovementioned integrated functional circuit and three sensors (temperature, pressure, and ultraviolet) is built. The milliwatt microsystem operates continuously with the TEHNG as the only power supply, achieving self-powered operations of sensing environmental variables and transmitting wireless data to a terminal in real time. This shows tremendous application potential in the IoT field.

Integrated hybrid sensing and microenergy for compact active microsystems.

Wearable electronics, as essential components of the Internet of Things (IoT), have attracted widespread attention, and the trend is to configure attractive wearable smart microsystems by integrating sensing, powering, and other functions. Herein, we developed an elastic hybrid triboelectric-electromagnetic microenergy harvester (named EHTE) to realize hybrid sensing and microenergy simultaneously. This EHTE is a highly integrated triboelectric nanogenerator (TENG) and electromagnetic nanogenerator (EMG). Based on the triboelectric-electromagnetic hybrid mechanism, an enhanced electrical output of the EHTE was achieved successfully, which demonstrates the feasibility of the EHTE for microelectronics powering. Moreover, with the merits of the EMG, the developed hybrid microenergy harvester integrated both active frequency sensing and passive inductive sensing capabilities. Specifically, the almost linear correlation of the electromagnetic outputs to the frequencies of the external stimulus endowed the proposed EHTE with an outstanding active frequency sensing ability. In addition, due to the unique structural configuration of the EMG (i.e., a conductive permanent magnet (PM), hybrid deformation layer, and flexible printed circuit board (FPCB) coil), an opportunity was provided for the developed EHTE to serve as a passive inductive sensor based on the eddy current effect (i.e., a form of electromagnetic induction). Therefore, the developed EHTE successfully achieved the integration of hybrid sensing (i.e., active frequency sensing and passive inductive sensing) and microenergy (i.e., the combination of electromagnetic effect and triboelectric effect) within a single device, which demonstrates the potential of this newly developed EHTE for wearable electronic applications, especially in applications of compact active microsystems.

Wearable Multi-Functional Sensing Technology for Healthcare Smart Detection.

In recent years, considerable research efforts have been devoted to the development of wearable multi-functional sensing technology to fulfill the requirements of healthcare smart detection, and much progress has been achieved. Due to the appealing characteristics of flexibility, stretchability and long-term stability, the sensors have been used in a wide range of applications, such as respiration monitoring, pulse wave detection, gait pattern analysis, etc. Wearable sensors based on single mechanisms are usually capable of sensing only one physiological or motion signal. In order to measure, record and analyze comprehensive physical conditions, it is indispensable to explore the wearable sensors based on hybrid mechanisms and realize the integration of multiple smart functions. Herein, we have summarized various working mechanisms (resistive, capacitive, triboelectric, piezoelectric, thermo-electric, pyroelectric) and hybrid mechanisms that are incorporated into wearable sensors. More importantly, to make wearable sensors work persistently, it is meaningful to combine flexible power units and wearable sensors and form a self-powered system. This article also emphasizes the utility of self-powered wearable sensors from the perspective of mechanisms, and gives applications. Furthermore, we discuss the emerging materials and structures that are applied to achieve high sensitivity. In the end, we present perspectives on the outlooks of wearable multi-functional sensing technology.

Silicone Rubber Based-Conductive Composites for Stretchable "All-in-One" Microsystems.

Wearable electronics with development trends such as miniaturization, multifunction, and smart integration have become an important part of the Internet of Things (IoT) and have penetrated various sectors of modern society. To meet the increasing demands of wearable electronics in terms of deformability and conformability, many efforts have been devoted to overcoming the nonstretchable and poor conformal properties of traditional functional materials and endowing devices with outstanding mechanical properties. One of the promising approaches is composite engineering in which traditional functional materials are incorporated into the various polymer matrices to develop different kinds of functional composites and construct different functions of stretchable electronics. Herein, we focus on the approach of composite engineering and the polymer matrix of silicone rubber (SR), and we summarize the state-of-the-art details of silicone rubber-based conductive composites (SRCCs), including a summary of their conductivity mechanisms and synthesis methods and SRCC applications for stretchable electronics. For conductivity mechanisms, two conductivity mechanisms of SRCC are emphasized: percolation theory and the quantum tunneling mechanism. For synthesis methods of SRCCs, four typical approaches to synthesize different kinds of SRCCs are investigated: mixing/blending, infiltration, ion implantation, and in situ formation. For SRCC applications, different functions of stretchable electronics based on SRCCs for interconnecting, sensing, powering, actuating, and transmitting are summarized, including stretchable interconnects, sensors, nanogenerators, antennas, and transistors. These functions reveal the feasibility of constructing a stretchable all-in-one self-powered microsystem based on SRCC-based stretchable electronics. As a prospect, this microsystem is expected to integrate the functional sensing modulus, the energy harvesting modulus, and the process and response modulus together to sense and respond to environmental stimulations and human physiological signals.

Reducing the Excess Activin Signaling Rescues Muscle Degeneration in Myotonic Dystrophy Type 2 Drosophila Model.

Expanded non-coding RNA repeats of CCUG are the underlying genetic causes for myotonic dystrophy type 2 (DM2). There is an urgent need for effective medications and potential drug targets that may alleviate the progression of the disease. In this study, 3140 small-molecule drugs from FDA-approved libraries were screened through lethality and locomotion phenotypes using a DM2 Drosophila model expressing 720 CCTG repeats in the muscle. We identified ten effective drugs that improved survival and locomotor activity of DM2 flies, including four that share the same predicted targets in the TGF-ß pathway. The pathway comprises two major branches, the Activin and BMP pathways, which play critical and complex roles in skeletal development, maintenance of homeostasis, and regeneration. The Drosophila model recapitulates pathological features of muscle degeneration in DM2, displaying shortened lifespan, a decline in climbing ability, and progressive muscle degeneration. Increased levels of p-smad3 in response to activin signaling were observed in DM2 flies. Decreased levels of activin signaling using additional specific inhibitors or genetic method ameliorated climbing defects, crushed thoraxes, structure, and organization of muscle fibers. Our results demonstrate that a decrease in activin signaling is sufficient to rescue muscle degeneration and is, therefore, a potential therapeutic target for DM2.

Electron-Ion Coupling Mechanism to Construct Stable Output Performance Nanogenerator.

Recently, triboelectric nanogenerators (TENGs) have been promoted as an effective technique for ambient energy harvesting, given their large power density and high energy conversion efficiency. However, traditional TENGs based on the combination of triboelectrification effect and electrostatic induction have proven susceptible to environmental influence, which intensively restricts their application range. Herein, a new coupling mechanism based on electrostatic induction and ion conduction is proposed to construct flexible stable output performance TENGs (SOP-TENGs). The calcium chloride doped-cellulose nanofibril (CaCl2-CNF) film made of natural carrots was successfully introduced to realize this coupling, resulting from its intrinsic properties as natural nanofibril hydrogel serving as both triboelectric layer and electrode. The coupling of two conductive mechanisms of SOP-TENG was comprehensively investigated through electrical measurements, including the effects of moisture content, relative humidity, and electrode size. In contrast to the conventional hydrogel ionotronic TENGs that require moisture as the carrier for ion transfer and use a hydrogel layer as the electrode, the use of a CaCl2-CNF film (i.e., ion-doped natural hydrogel layer) as a friction layer in the proposed SOP-TENG effectively realizes a superstable electrical output under varying moisture contents and relative humidity due to the compound transfer mechanism of ions and electrons. This new working principle based on the coupling of electrostatic induction and ion conduction opens a wider range of applications for the hydrogel ionotronic TENGs, as the superstable electrical output enables them to be more widely applied in various complex environments to supply energy for low-power electronic devices.

Wearable multi-sensing double-chain thermoelectric generator.

Wearable electronics play a crucial role in advancing the rapid development of artificial intelligence, and as an attractive future vision, all-in-one wearable microsystems integrating powering, sensing, actuating and other functional components on a single chip have become an appealing tendency. Herein, we propose a wearable thermoelectric generator (ThEG) with a novel double-chain configuration to simultaneously realize sustainable energy harvesting and multi-functional sensing. In contrast to traditional single-chain ThEGs with the sole function of thermal energy harvesting, each individual chain of the developed double-chain thermoelectric generator (DC-ThEG) can be utilized to scavenge heat energy, and moreover, the combination of the two chains can be employed as functional sensing electrodes at the same time. The mature mass-fabrication technology of screen printing was successfully introduced to print n-type and p-type thermoelectric inks atop a polymeric substrate to form thermocouples to construct two independent chains, which makes this DC-ThEG flexible, high-performance and cost-efficient. The emerging material of silk fibroin was employed to cover the gap of the fabricated two chains to serve as a functional layer for sensing the existence of liquid water molecules in the air and the temperature. The powering and sensing functions of the developed DC-ThEG and their interactions were systematically studied via experimental measurements, which proved the DC-ThEG to be a robust multi-functional power source with a 151 mV open-circuit voltage. In addition, it was successfully demonstrated that this DC-ThEG can convert heat energy to achieve a 3.3 V output, matching common power demands of wearable electronics, and harvest biothermal energy to drive commercial electronics (i.e., a calculator). The integration approach of powering and multi-functional sensing based on this new double-chain configuration might open a new chapter in advanced thermoelectric generators, especially in the applications of all-in-one self-powered microsystems.

Single-Layer Triboelectric Nanogenerators Based on Ion-Doped Natural Nanofibrils.

As emerging ambient energy harvesting technology, triboelectric nanogenerators (TENGs) have proven to be a robust power source and have demonstrated the unique ability to power micro-nano electronics autonomously to form self-powered devices. Although four working modes of TENGs have been developed to promote the feasibility of self-powered micro-nano systems, the relatively complicated structure composed of multilayer and movable components limits the practical applications of TENGs. Herein, we propose a single-layer triboelectric nanogenerator (SL-TENG) based on ion-doped natural nanofibrils. Compared with the simplest mode of currently existing TENGs, i.e., the single-electrode type, this novel single-electrode TENG further simplifies the configuration by the removal of the dielectric layer. The underlying mechanism of the proposed SL-TENG is comprehensively investigated through electrical measurements and the analysis of the effect of ion species at different concentrations. In contrast to conventional TENGs that require electrodes to realize charge transfer, it is revealed that the ions doped into natural nanofibrils effectively realize charge transfer due to the separation and migration of cations and anions. This new working principle based on the combination of electrons and ions enables TENGs to show greater potential for applications since the ultrasimple single-layer configuration enables them to be more easily integrated with other electronic components; additionally, the whole device of the proposed SL-TENG is biodegradable because the natural nanofibrils are completely extracted from carrots.

[Influence of the depth of retained denatured dermis on the survival rate of grafted skin in burn swine with deep partial-thickness burn].

OBJECTIVE: To explore the influence of the thickness of retained denatured dermis on the survival rate of grafted skin in swine with deep partial-thickness burn. METHODS: Four deep partial-thickness wounds were reproduced respectively on both sides of spine in 7 Chinese domestic pigs. The wounds of 6 pigs were divided into 0.25, 0.50, 0.75, and 1.00 mm groups with 12 wounds in each group according to the random number table. Tangential excision and auto-skin grafting were performed. Before the tangential excision, 1 tissue specimen was harvested from the center of each remaining wound for the estimation of the depth of burn, and histological observation was done. After the tangential excision, 1 tissue specimen was harvested from the area near the center of each wound for the measurement of the depth of retained denatured dermis with histological examination. The 8 wounds of one pig were set as the control group, and the operation was done, and then they were treated with exposure treatment after biopsy specimens were taken with above-mentioned method. The general condition of wounds in 5 groups was observed from immediately after injury to post injury month (PIM) 3. On post injury day (PID) 7, the survival rate of grafted skin was observed in 0.25, 0.50, 0.75, and 1.00 mm groups. Wound healing time was recorded. At PIM 3, the specimens were harvested from the wounds of 5 groups, and their ultra microstructures were observed by transmission electron microscope. Data were processed with rank-sum test, one-way analysis of variance, and LSD test. RESULTS: The depth of the burn tissue was (1.120 ± 0.211) mm. The depths of retained denatured dermis in 0.25, 0.50, 0.75, and 1.00 mm groups were respectively (0.830 ± 0.031), (0.701 ± 0.010), (0.382 ± 0.031), and (0.141 ± 0.040) mm. At PID 8, all grafted skin in 0.25 and 0.50 mm groups became necrotic; most grafted skin in 0.75 mm group was necrotic; most grafted skin in 1.00 mm group survived with only a few became necrotic and separated from the wounds. The scabs were gradually separated from the wounds of control group. On PID 15, the grafted skin which did not survive in 0.25, 0.50, and 0.75 mm groups was gradually separated from the wounds with exudate forming scab on the surface in varying degrees, while the wounds in 1.00 mm group were all healed, and the incidence of scabs formation was highest in control group. At PIM 3, scar contraction was found in 0.25, 0.50, 0.75 mm groups and control group, while no obvious scar was observed in 1.00 mm group. There were statistically significant differences in the survival rate of grafted skin in 0.25, 0.50, 0.75, and 1.00 mm groups (χ(2) = 19.421, P < 0.001). The survival rate was the highest in 1.00 mm group [70% (60%, 80%)], while the survival rate was 20% (0, 30%) in 0.75 mm group, and it was in both 0.25 and 0.50 mm groups with non-survival of all the grafted skin. There were statistically significant differences in the wound healing time among 5 groups (F = 41.450, P < 0.001). The wound healing time in 0.25 and 0.50 mm groups were respectively (18.2 ± 1.5), and (18.7 ± 2.3) d, not statistically significant different from that of control group [(18.4 ± 1.7) d, P values both above 0.05]. The wound healing time in 0.75 mm group [(14.9 ± 2.6) d] was significantly different from those of 0.25, 0.50 mm groups and control group (P values all below 0.01). The wound healing time in 1.00 mm group [(9.5 ± 1.2) d] was significantly shorter compared with that of the other 4 groups (P values all below 0.01). Before tangential excision, the zone of infiltration of the inflammatory cells was observed in the deep dermis of wounds in 5 groups. After tangential excision and before auto-skin grafting, the depth from the fault surface to the zone of infiltration of the inflammatory cells varied in 0.25, 0.50, 0.75, and 1.00 mm groups while more inflammatory cells were observed in control group. At PIM 3, many fibroblasts were observed in the dermis of wounds in 1.00 mm group with abundant rough endoplasmic reticulum and basically intact organelles. CONCLUSIONS: Performing autologous skin grafting on deep partial-thickness burn, in which the depth of retained denatured dermis was 0.10 mm, may help regenerate dermal function and alleviate scar formation.