Electrically Responsive Materials and Devices Directly Driven by the High Voltage of Triboelectric Nanogenerators

Smart materials with electrically responsive characteristics and devices relying on different electrostatic effects can be directly driven by triboelectric nanogenerators (TENGs). The open circuit voltage from a TENG can easily reach thousands of volts with a separation distance of a few millimeters and this high output voltage can be used to effectively drive or control some devices with high internal resistance. This kind of combination is the most straightforward way for achieving a self‐powered smart system. Hence, a detailed survey of electrically responsive materials and devices that can be successfully combined with TENG is summarized, including dielectric elastomers, piezoelectric materials, ferroelectric materials, electrostatic manipulators, electrostatic air cleaners, and field emission and mass spectrometers. Moreover, key factors in determining suitable materials or devices to work with TENG are clarified and an in‐depth discussion of the current challenges related to these combined systems is provided. With the cost‐effectiveness and simple manufacturing process, these TENG‐based composite systems have great application prospects in the field of smart mechanics, human–machine interaction systems, intelligent storage systems, self‐powered microfluidic chips, portable mass spectrometers, and so on.     

Removal of Microparticles by Ciliated Surfaces—an Experimental Study

Biological cilia are versatile hair‐like organelles that are very efficient in manipulating particles for, e.g., feeding, antifouling, and cell transport. Inspired by the versatility of cilia, this paper experimentally demonstrates active particle‐removal by self‐cleaning surfaces that are fully or partially covered with micromolded magnetic artificial cilia (MAC). Actuated by a rotating magnet, the MAC can perform a tilted conical motion, which leads to the removal of spherical particles of different sizes in water, as well as irregular‐shaped sand grains both in water and in air. These findings can contribute to the development of novel particulate manipulation and self‐cleaning/antifouling surfaces, which can be applied, e.g., to prevent fouling of (bio)sensors in lab‐on‐a‐chip devices, and to prevent biofouling of submerged surfaces such as marine sensors and water quality analyzers.     

Thermodynamically Controlled Self‐Assembly of Hierarchically Staggered Architecture as an Osteoinductive Alternative to Bone Autografts

Osteoinductive synthetic biomaterials for replacing autografts can be developed by mimicking bone hierarchy and surface topography for host cell recruitment and differentiation. Until now, it has been challenging to reproduce a bone‐like staggered hierarchical structure since the energy change underlying synthetic pathways in vitro is essentially different from that of the natural process in vivo. Herein, a bone‐like hierarchically staggered architecture is reproduced under thermodynamic control involving two steps: fabrication of a high‐energy polyacrylic acid‐calcium intermediate and selective mineralization in collagenous gap regions driven by an energetically downhill process. The intermediate energy interval could easily be adjusted to determine different mineralization modes, with distinct morphologies and biofunctions. Similar to bone autografts, the staggered architecture offers a bone‐specific microenvironment for stem cell recruitment and multidifferentiation in vitro, and induces neo‐bone formation with bone marrow blood vessels by host stem cell homing in vivo. This work provides a novel perspective for an in vitro simulating biological mineralization process and proof of concept for the clinical application of smart biomaterials.     

Transcatheter Self‐Powered Ultrasensitive Endocardial Pressure Sensor

Changes in endocardial pressure (EP) have important clinical significance for heart failure patients with impaired cardiac function. As a vital parameter for evaluating cardiac function, EP is commonly monitored by invasive and expensive cardiac catheterization, which is not feasible for long‐term and continuous data collection. In this work, a miniaturized, flexible, and self‐powered endocardial pressure sensor (SEPS) based on triboelectric nanogenerator (TENG), which is integrated with a surgical catheter for minimally invasive implantation, is reported. In a porcine model, SEPS is implanted into the left ventricle and the left atrium. The SEPS has a good response both in low‐ and high‐pressure environments. The SEPS achieves the ultrasensitivity, real‐time monitoring, and mechanical stability in vivo. An excellent linearity (R ² = 0.997) with a sensitivity of 1.195 mV mmHg^?1 is obtained. Furthermore, cardiac arrhythmias such as ventricular fibrillation and ventricular premature contraction can also be detected by SEPS. The device may promote the development of miniature implantable medical sensors for monitoring and diagnosis of cardiovascular diseases.     

A Modular Vaccine Platform Combining Self‐Assembled Peptide Cages and Immunogenic Peptides

Subunit vaccines use delivery platforms to present minimal antigenic components for immunization. The benefits of such systems include multivalency, self‐adjuvanting properties, and more specific immune responses. Previously, the design, synthesis, and characterization of self‐assembling peptide cages (SAGEs) have been reported. In these, de novo peptides are combined to make hubs that assemble into nanoparticles when mixed in aqueous solution. Here it is shown that SAGEs are nontoxic particles with potential as accessible synthetic peptide scaffolds for the delivery of immunogenic components. To this end, SAGEs functionalized with the model antigenic peptides tetanus toxoid_632‐651 and ovalbumin_323‐339 drive antigen‐specific responses both in vitro and in vivo, eliciting both CD4⁺ T cell and B cell responses. Additionally, SAGEs functionalized with the antigenic peptide hemagglutinin_518‐526 from the influenza virus are also able to drive a CD8⁺ T cell response in vivo. This work demonstrates the potential of SAGEs to act as a modular scaffold for antigen delivery, capable of inducing and boosting specific and tailored immune responses.     

Injectable Self‐Healing Antibacterial Bioactive Polypeptide‐Based Hybrid Nanosystems for Efficiently Treating Multidrug Resistant Infection,Skin‐Tumor Therapy,and Enhancing Wound Healing

The surgical procedure in skin‐tumor therapy usually results in cutaneous defects, and multidrug‐resistant bacterial infection could cause chronic wounds. Here, for the first time, an injectable self‐healing antibacterial bioactive polypeptide‐based hybrid nanosystem is developed for treating multidrug resistant infection, skin‐tumor therapy, and wound healing. The multifunctional hydrogel is successfully prepared through incorporating monodispersed polydopamine functionalized bioactive glass nanoparticles (BGN@PDA) into an antibacterial F127‐ε‐Poly‐L‐lysine hydrogel. The nanocomposites hydrogel displays excellent self‐healing and injectable ability, as well as robust antibacterial activity, especially against multidrug‐resistant bacteria in vitro and in vivo. The nanocomposites hydrogel also demonstrates outstanding photothermal performance with (near‐infrared laser irradiation) NIR irradiation, which could effectively kill the tumor cell (>90%) and inhibit tumor growth (inhibition rate up to 94%) in a subcutaneous skin‐tumor model. In addition, the nanocomposites hydrogel effectively accelerates wound healing in vivo. These results suggest that the BGN‐based nanocomposite hydrogel is a promising candidate for skin‐tumor therapy, wound healing, and anti‐infection. This work may offer a facile strategy to prepare multifunctional bioactive hydrogels for simultaneous tumor therapy, tissue regeneration, and anti‐infection.     

Research of the adaptive control on modulation factor for PSR fly‐back PSM converter

The energy balance (EB) model of a primary side regulation (PSR) fly‐back converter in the discontinuous conduction mode (DCM) is discussed in this paper. Based on this EB model, the stability of a PSR fly‐back converter in the pulse skipping mode (PSM) is analyzed, and a self‐adapting modulation factor control strategy is proposed. Theoretical analysis and simulation results show that by saving an optocoupler and correlative circuits, which are necessary in traditional PSM fly‐back converters, the modulation factor tolerance controlled by this method is 1.26% on average, corresponding to the ideal value. Compared with traditional fly‐back PSM controllers, the power saved in the sampler/comparator modules is 87% on average for a load range of 1 Ω to 1 kΩ.     

An Adaptable Nanoplatform for Integrating Anatomic and Functional Magnetic Resonance Imaging under a 3.0 T Magnetic Field

It is well known that acidic tumor microenvironment (TME) is very important for tumor' growth, metastasis, and drug resistance. In addition, accurate diagnosis of the solid tumors' acidic microenviroment based on the precise location of their site is especially essential for the further treatment and prognostic evaluation of cancer. Although magnetic resonance imaging (MRI) is widely used for clinical cancer diagnosis, there are still enormous challenges left for developing MRI agents which integrate anatomic imaging for tumor site location with functional imaging for pH evaluation, especially for medium or high magnetic field machines. Herein, an innovative strategy is proposed to incorporate anatomic imaging (T₁‐weighted imaging, T₁WI) with functional imaging (susceptibility weighted imaging, SWI) using one 3.0 T MRI scanner on an adaptable nanoplatform namely, NaGdF₄@polydopamine@polyethylene glycol (PEG), which can self‐aggregate under the specific low pH in TME to realize regulatory susceptibility. Moreover, the nanoplatform performs well in tumor accurately location as well as pH sensitively perception. Most importantly, the strategy not only fuses two MRI models on one nanoplatform using one 3.0 T machine to extend the application range but also provides a new insight for the design of other novel imaging agents.     

A Monocharged Electret Nanogenerator‐Based Self‐Powered Device for Pressure and Tactile Sensor Applications

This study reports a self‐powered pressure sensor based on a monocharged electret nanogenerator (MENG). The sensor exhibits great advantages in terms of high reliability, ease of fabrication, and relatively high sensitivity. The working mechanism of the MENG sensor is studied by both theoretical derivations and finite element analyses to determine the electric potential distribution during the device operation. The MENG sensor exhibits a stable open circuit voltage ≈10 V at a 30.8 kPa pressure and a corresponding sensitivity of 325 mV kPa^?1. The stability testing result shows that the device has only ≈5% attenuation after 10 000 cycles of repeated testing at 30.8 kPa pressure. Furthermore, it is found that the MENG sensor responds not only to a dynamic force but also a static force. Finally, a sensor array consisting of nine MENG sensor elements is fabricated. The testing results from the sensor array also reveal that a single touch of the sensor element can immediately light up an LED light at the corresponding position. This device holds great promise for use in future tactile sensors and artificial skin applications.     

Hydrogen‐Bonded Two‐Component Ionic Crystals Showing Enhanced Long‐Lived Room‐Temperature Phosphorescence via TADF‐Assisted Förster Resonance Energy Transfer

Molecular room‐temperature phosphorescent (RTP) materials with long‐lived excited states have attracted widespread attention in the fields of optical imaging, displays, and sensors. However, accessing ultralong RTP systems remains challenging and examples are still limited to date. Herein, a thermally activated delayed fluorescence (TADF)‐assisted energy transfer route for the enhancement of persistent luminescence with an RTP lifetime as high as 2 s, which is higher than that of most state‐of‐the‐art RTP materials, is proposed. The energy transfer donor and acceptor species are based on the TADF and RTP molecules, which can be self‐assembled into two‐component ionic salts via hydrogen‐bonding interactions. Both theoretical and experimental studies illustrate the occurrence of effective Förster resonance energy transfer (FRET) between donor and acceptor molecules with an energy transfer efficiency as high as 76%. Moreover, the potential for application of the donor–acceptor cocrystallized materials toward information security and personal identification systems is demonstrated, benefitting from their varied afterglow lifetimes and easy recognition in the darkness. Therefore, the work described in this study not only provides a TADF‐assisted FRET strategy toward the construction of ultralong RTP, but also yields hydrogen‐bonding‐assembled two‐component molecular crystals for potential encryption and anti‐counterfeiting applications.