On‐Skin Triboelectric Nanogenerator and Self‐Powered Sensor with Ultrathin Thickness and High Stretchability

Researchers have devoted a lot of efforts on pursuing light weight and high flexibility for the wearable electronics, which also requires the related energy harvesting devices to have ultrathin thickness and high stretchability. Hence, an elastic triboelectric nanogenerator (TENG) is proposed that can serve as the second skin on human body. The total thickness of this TENG is about 102 µm and the device can work durably under a strain of 100%. The carbon grease is painted on the surface of elastomer film to work as stretchable electrode and thus the fine geometry control of the electrode can be achieved. This elastic TENG can even work on the human fingers without disturbing body movement. The open‐circuit voltage and short‐circuit current from the device with a contact area of 9 cm² can reach 115 V and 3 µA, respectively. Two kinds of self‐powered sensor systems with optimized identification strategies are also designed to demonstrate the application possibility of this elastic TENG. The superior characteristics of ultrathin thickness, high stretchability, and fine geometry control of this TENG can promote many potential applications in the field of wearable self‐powered sensory system, electronics skin, artificial muscles, and soft robotics.     

A Shape‐Adaptive Thin‐Film‐Based Approach for 50% High‐Efficiency Energy Generation Through Micro‐Grating Sliding Electrification

Effectively harvesting ambient mechanical energy is the key for realizing self‐powered and autonomous electronics, which addresses limitations of batteries and thus has tremendous applications in sensor networks, wireless devices, and wearable/implantable electronics, etc. Here, a thin‐film‐based micro‐grating triboelectric nanogenerator (MG‐TENG) is developed for high‐efficiency power generation through conversion of mechanical energy. The shape‐adaptive MG‐TENG relies on sliding electrification between complementary micro‐sized arrays of linear grating, which offers a unique and straightforward solution in harnessing energy from relative sliding motion between surfaces. Operating at a sliding velocity of 10 m/s, a MG‐TENG of 60 cm² in overall area, 0.2 cm³ in volume and 0.6 g in weight can deliver an average output power of 3 W (power density of 50 mW cm^?2 and 15 W cm^?3) at an overall conversion efficiency of ～50%, making it a sufficient power supply to regular electronics, such as light bulbs. The scalable and cost‐effective MG‐TENG is practically applicable in not only harvesting various mechanical motions but also possibly power generation at a large scale.     

A New Facile Route to Flexible and Semi‐Transparent Electrodes Based on Water Exfoliated Graphene and their Single‐Electrode Triboelectric Nanogenerator

Wearable technologies are driving current research efforts to self‐powered electronics, for which novel high‐performance materials such as graphene and low‐cost fabrication processes are highly sought.The integration of high‐quality graphene films obtained from scalable water processing approaches in emerging applications for flexible and wearable electronics is demonstrated. A novel method for the assembly of shear exfoliated graphene in water, comprising a direct transfer process assisted by evaporation of isopropyl alcohol is developed. It is shown that graphene films can be easily transferred to any target substrate such as paper, flexible polymeric sheets and fibers, glass, and Si substrates. By combining graphene as the electrode and poly(dimethylsiloxane) as the active layer, a flexible and semi‐transparent triboelectric nanogenerator (TENG) is demonstrated for harvesting energy. The results constitute a new step toward the realization of energy harvesting devices that could be integrated with a wide range of wearable and flexible technologies, and opens new possibilities for the use of TENGs in many applications such as electronic skin and wearable electronics.     

Porous Silicon Nanoneedles Modulate Endocytosis to Deliver Biological Payloads

Owing to their ability to efficiently deliver biological cargo and sense the intracellular milieu, vertical arrays of high aspect ratio nanostructures, known as nanoneedles, are being developed as minimally invasive tools for cell manipulation. However, little is known of the mechanisms of cargo transfer across the cell membrane‐nanoneedle interface. In particular, the contributions of membrane piercing, modulation of membrane permeability and endocytosis to cargo transfer remain largely unexplored. Here, combining state‐of‐the‐art electron and scanning ion conductance microscopy with molecular biology techniques, it is shown that porous silicon nanoneedle arrays concurrently stimulate independent endocytic pathways which contribute to enhanced biomolecule delivery into human mesenchymal stem cells. Electron microscopy of the cell membrane at nanoneedle sites shows an intact lipid bilayer, accompanied by an accumulation of clathrin‐coated pits and caveolae. Nanoneedles enhance the internalization of biomolecular markers of endocytosis, highlighting the concurrent activation of caveolae‐ and clathrin‐mediated endocytosis, alongside macropinocytosis. These events contribute to the nanoneedle‐mediated delivery (nanoinjection) of nucleic acids into human stem cells, which distribute across the cytosol and the endolysosomal system. This data extends the understanding of how nanoneedles modulate biological processes to mediate interaction with the intracellular space, providing indications for the rational design of improved cell‐manipulation technologies.     

High‐Performance Al/PDMS TENG with Novel Complex Morphology of Two‐Height Microneedles Array for High‐Sensitivity Force‐Sensor and Self‐Powered Application

Triboelectric nanogenerators (TENGs) are widely applied to self‐powered devices and force sensors. TENGs consist of the electrode‐layer frequently made of high‐cost conductors (Ag, Au, ITO) and the tribo‐layer of rigid negative‐triboelectricity fluoropolymers (PTFE, FEP). The surface morpholoy is studied for enhancing performance. Here, a high‐performance Al/PDMS‐TENG is proposed with a complex morphology of overlapped deep two‐height microneedles (OL‐DTH‐MN) fabricated by the integrated process of low‐cost CO₂ laser ablation and PDMS casting for self‐powered devices and high‐sensitivity force/pressure sensors. The high open‐circuit voltage and short‐circuit current of the OL‐DTH‐MN‐TENG are 167 V and 129.3 µA. Also, the sensitivity of the force/pressure sensor of the OL‐DTH‐MN‐TENG is very high, 1.03 V N^?1 and about 3.11 V kPa^?1, at an area of 30 cm² that is much higher than the sensitivity of about 0.18–0.414 V N^?1 and 0.013–0.29 V kPa^?1 of conventional TENG sensors. Meanwhile, the high‐performance OL‐DTH‐MN‐TENG not only exhibits the energy storage capability of charging a 0.1 µF capacitor to 2.75 V at 1.19 s, to maximum 3.22 V, but also activates various self‐powered devices including lighting colorful 226 LEDs connected in series, the “2020‐ME‐NCKU” advertising board, a calculator and a temperature sensor. Numerical simulation is also performed to support the experiments.     

3D Orthogonal Woven Triboelectric Nanogenerator for Effective Biomechanical Energy Harvesting and as Self‐Powered Active Motion Sensors

The development of wearable and large‐area energy‐harvesting textiles has received intensive attention due to their promising applications in next‐generation wearable functional electronics. However, the limited power outputs of conventional textiles have largely hindered their development. Here, in combination with the stainless steel/polyester fiber blended yarn, the polydimethylsiloxane‐coated energy‐harvesting yarn, and nonconductive binding yarn, a high‐power‐output textile triboelectric nanogenerator (TENG) with 3D orthogonal woven structure is developed for effective biomechanical energy harvesting and active motion signal tracking. Based on the advanced 3D structural design, the maximum peak power density of 3D textile can reach 263.36 mW m^?2 under the tapping frequency of 3 Hz, which is several times more than that of conventional 2D textile TENGs. Besides, its collected power is capable of lighting up a warning indicator, sustainably charging a commercial capacitor, and powering a smart watch. The 3D textile TENG can also be used as a self‐powered active motion sensor to constantly monitor the movement signals of human body. Furthermore, a smart dancing blanket is designed to simultaneously convert biomechanical energy and perceive body movement. This work provides a new direction for multifunctional self‐powered textiles with potential applications in wearable electronics, home security, and personalized healthcare.     

Inductor‐Free Wireless Energy Delivery via Maxwell's Displacement Current from an Electrodeless Triboelectric Nanogenerator

Wireless power delivery has been a dream technology for applications in medical science, security, radio frequency identification (RFID), and the internet of things, and is usually based on induction coils and/or antenna. Here, a new approach is demonstrated for wireless power delivery by using the Maxwell's displacement current generated by an electrodeless triboelectric nanogenerator (TENG) that directly harvests ambient mechanical energy. A rotary electrodeless TENG is fabricated using the contact and sliding mode with a segmented structure. Due to the leakage of electric field between the segments during relative rotation, the generated Maxwell's displacement current in free space is collected by metal collectors. At a gap distance of 3 cm, the output wireless current density and voltage can reach 7 µA cm⁻² and 65 V, respectively. A larger rotary electrodeless TENG and flexible wearable electrodeless TENG are demonstrated to power light‐emitting diodes (LEDs) through wireless energy delivery. This innovative discovery opens a new avenue for noncontact, wireless energy transmission for applications in portable and wearable electronics.     

Photosensitizer‐Incorporated Quadruplex DNA‐Gated Nanovechicles for Light‐Triggered,Targeted Dual Drug Delivery to Cancer Cells

A novel light‐operated vehicle for targeted intracellular drug delivery is constructed using photosensitizer‐incorporated G‐quadruplex DNA‐capped mesoporous silica nanoparticles. Upon light irradiation, the photosensitizer generates ROS, causing the DNA capping to be cleaved and allowing cargo to be released. Importantly, this platform makes it possible to develop a drug‐carrier system for the synergistic combination of chemotherapy and PDT for cancer treatment with spatial/temporal control. Furthermore, the introducing of targeting ligands further improves tumor targeting efficiency. The excellent biocompatibility, cell‐specific intracellular drug delivery, and cellular uptake properties set up the basis for future biomedical application that require in vivo controlled, targeted drug delivery.     

Printable Fabrication of a Fully Integrated and Self‐Powered Sensor System on Plastic Substrates

Wearable and portable devices with desirable flexibility, operational safety, and long cruising time, are in urgent demand for applications in wireless communications, multifunctional entertainments, personal healthcare monitoring, etc. Herein, a monolithically integrated self‐powered smart sensor system with printed interconnects, printed gas sensor for ethanol and acetone detection, and printable supercapacitors and embedded solar cells as energy sources, is successfully demonstrated in a wearable wristband fashion by utilizing inkjet printing as a proof‐of‐concept. In such a “wearable wristband”, the harvested solar energy can either directly drive the sensor and power up a light‐emitting diode as a warning signal, or can be stored in the supercapacitors in a standby mode, and the energy released from supercapacitors can compensate the intermittency of light illumination. To the best of our knowledge, the demonstration of such a self‐powered sensor system integrated onto a single piece of flexible substrate in a printable and additive manner has not previously been reported. Particularly, the printable supercapacitors deliver an areal capacitance of 12.9 mF cm^?2 and the printed SnO₂ gas sensor shows remarkable detection sensitivity under room temperature. The printable strategies for device fabrication and system integration developed here show great potency for scalable and facile fabrication of a variety of wearable devices.     

Theory of Sliding‐Mode Triboelectric Nanogenerators

The triboelectric nanogenerator (TENG) is a powerful approach toward new energy technology, especially for portable electronics. A theoretical model for the sliding‐mode TENG is presented in this work. The finite element method was utilized to characterize the distributions of electric potential, electric field, and charges on the metal electrodes of the TENG. Based on the FEM calculation, the semi‐analytical results from the interpolation method and the analytical V‐Q‐x relationship are built to study the sliding‐mode TENG. The analytical V‐Q‐x equation is validated through comparison with the semi‐analytical results. Furthermore, based on the analytical V‐Q‐x equation, dynamic output performance of sliding‐mode TENG is calculated with arbitrary load resistance, and good agreement with experimental data is achieved. The theory presented here is a milestone work for in‐depth understanding of the working mechanism of the sliding‐mode TENG, and provides a theoretical basis for further enhancement of the sliding‐mode TENG for both energy scavenging and self‐powered sensor applications.     

Service Behavior of Multifunctional Triboelectric Nanogenerators

Triboelectric nanogenerators (TENGs) or TENG‐based self‐charging systems harvesting energy from ambient environment are promising power solution for electronics. The stable running remains a key consideration in view of potential complex application environment. In this work, a textile‐based tailorable multifunctional TENG (T‐TENG) is developed. The T‐TENG is used as self‐powered human body motion sensor, water energy harvester, and formed all textile‐based flexible self‐charging system by integrating with textile‐based supercapacitors. The service behavior and the mechanism of performance retention are also studied when the T‐TENG is damaged. As a self‐powered human body motion sensor, the T‐TENG maintains the stable properties when it is cut. As a water energy harvester, the T‐TENG is capable of scavenging mechanical energy from water efficiently even if it is damaged partly. Besides, the charge properties of the self‐charging system are systematically investigated when the T‐TENG is cut. The investigation on service behavior of T‐TENG and TENG‐based self‐charging system pushes forward the development of highly reliable electronics and is a guide for other nanodevices and nanosystems.     

Magnetic Tweezers‐Based 3D Microchannel Electroporation for High‐Throughput Gene Transfection in Living Cells

A novel high‐throughput magnetic tweezers‐based 3D microchannel electroporation system capable of transfecting 40 000 cells/cm² on a single chip for gene therapy, regenerative medicine, and intracellular detection of target mRNA for screening cellular heterogeneity is reported. A single cell or an ordered array of individual cells are remotely guided by programmable magnetic fields to poration sites with high (>90%) cell alignment efficiency to enable various transfection reagents to be delivered simultaneously into the cells. The present technique, in contrast to the conventional vacuum‐based approach, is significantly gentler on the cellular membrane yielding >90% cell viability and, moreover, allows transfected cells to be transported for further analysis. Illustrating the versatility of the system, the GATA2 molecular beacon is delivered into leukemia cells to detect the regulation level of the GATA2 gene that is associated with the initiation of leukemia. The uniform delivery and a sharp contrast of fluorescence intensity between GATA2 positive and negative cells demonstrate key aspects of the platform for gene transfer, screening and detection of targeted intracellular markers in living cells.     

Cancer Cell Membrane Camouflaged Semi‐Yolk@Spiky‐Shell Nanomotor for Enhanced Cell Adhesion and Synergistic Therapy

Cell adhesion of nanosystems is significant for efficient cellular uptake and drug delivery in cancer therapy. Herein, a near‐infrared (NIR) light‐driven biomimetic nanomotor is reported to achieve the improved cell adhesion and cellular uptake for synergistic photothermal and chemotherapy of breast cancer. The nanomotor is composed of carbon@silica (C@SiO₂) with semi‐yolk@spiky‐shell structure, loaded with the anticancer drug doxorubicin (DOX) and camouflaged with MCF‐7 breast cancer cell membrane (i.e., mC@SiO₂@DOX). Such biomimetic mC@SiO₂@DOX nanomotors display efficient self‐thermophoretic propulsion due to a thermal gradient generated by asymmetrically spatial distribution. Moreover, the MCF‐7 cancer cell membrane coating can remarkably reduce the bioadhesion of nanomotors in biological medium and exhibit highly specific self‐recognition of the source cell line. The combination of effective propulsion and homologous targeting dramatically improves cell adhesion and the resultant cellular uptake efficiency in vitro from 26.2% to 67.5%. Therefore, the biomimetic mC@SiO₂@DOX displays excellent synergistic photothermal and chemotherapy with over 91% MCF‐7 cell growth inhibition rate. Such smart design of the fuel‐free, NIR light‐powered biomimetic nanomotor may pave the way for the application of self‐propelled nanomotors in biomedicine.     

Immune Cell‐Mediated Biodegradable Theranostic Nanoparticles for Melanoma Targeting and Drug Delivery

Although tremendous efforts have been made on targeted drug delivery systems, current therapy outcomes still suffer from low circulating time and limited targeting efficiency. The integration of cell‐mediated drug delivery and theranostic nanomedicine can potentially improve cancer management in both therapeutic and diagnostic applications. By taking advantage of innate immune cell's ability to target tumor cells, the authors develop a novel drug delivery system by using macrophages as both nanoparticle (NP) carriers and navigators to achieve cancer‐specific drug delivery. Theranostic NPs are fabricated from a unique polymer, biodegradable photoluminescent poly (lactic acid) (BPLP‐PLA), which possesses strong fluorescence, biodegradability, and cytocompatibility. In order to minimize the toxicity of cancer drugs to immune cells and other healthy cells, an anti‐BRAF V600E mutant melanoma specific drug (PLX4032) is loaded into BPLP‐PLA nanoparticles. Muramyl tripeptide is also conjugated onto the nanoparticles to improve the nanoparticle loading efficiency. The resulting nanoparticles are internalized within macrophages, which are tracked via the intrinsic fluorescence of BPLP‐PLA. Macrophages carrying nanoparticles deliver drugs to melanoma cells via cell–cell binding. Pharmacological studies also indicate that the PLX4032 loaded nanoparticles effectively kill melanoma cells. The “self‐powered” immune cell‐mediated drug delivery system demonstrates a potentially significant advancement in targeted theranostic cancer nanotechnologies.     

Highly Transparent,Stretchable, and Self‐Healing Ionic‐Skin Triboelectric Nanogenerators for Energy Harvesting and Touch Applications

Recently developed triboelectric nanogenerators (TENGs) act as a promising power source for self‐powered electronic devices. However, the majority of TENGs are fabricated using metallic electrodes and cannot achieve high stretchability and transparency, simultaneously. Here, slime‐based ionic conductors are used as transparent current‐collecting layers of TENG, thus significantly enhancing their energy generation, stretchability, transparency, and instilling self‐healing characteristics. This is the first demonstration of using an ionic conductor as the current collector in a mechanical energy harvester. The resulting ionic‐skin TENG (IS‐TENG) has a transparency of 92% transmittance, and its energy‐harvesting performance is 12 times higher than that of the silver‐based electronic current collectors. In addition, they are capable of enduring a uniaxial strain up to 700%, giving the highest performance compared to all other transparent and stretchable mechanical‐energy harvesters. Additionally, this is the first demonstration of an autonomously self‐healing TENG that can recover its performance even after 300 times of complete bifurcation. The IS‐TENG represents the first prototype of a highly deformable and transparent power source that is able to autonomously self‐heal quickly and repeatedly at room temperature, and thus can be used as a power supply for digital watches, touch sensors, artificial intelligence, and biointegrated electronics.     

Rapid,High‐Throughput,and Direct Molecular Beacon Delivery to Human Cancer Cells Using a Nanowire‐Incorporated and Pneumatic Pressure‐Driven Microdevice

Tracking and monitoring the intracellular behavior of mRNA is of paramount importance for understanding real‐time gene expression in cell biology. To detect specific mRNA sequences, molecular beacons (MBs) have been widely employed as sensing probes. Although numerous strategies for MB delivery into the target cells have been reported, many issues such as the cytotoxicity of the carriers, dependence on the random probability of MB transfer, and critical cellular damage still need to be overcome. Herein, we have developed a nanowire‐incorporated and pneumatic pressure‐driven microdevice for rapid, high‐throughput, and direct MB delivery to human breast cancer MCF‐7 cells to monitor survivin mRNA expression. The proposed microdevice is composed of three layers: a pump‐associated glass manifold layer, a monolithic polydimethylsiloxane (PDMS) membrane, and a ZnO nanowire‐patterned microchannel layer. The MB is immobilized on the ZnO nanowires by disulfide bonding, and the glass manifold and PDMS membrane serve as a microvalve, so that the cellular attachment and detachment on the MB‐coated nanowire array can be manipulated. The combination of the nanowire‐mediated MB delivery and the microvalve function enable the transfer of MB into the cells in a controllable way with high cell viability and to detect survivin mRNA expression quantitatively after docetaxel treatment.     

Self‐Powered Pulse Sensor for Antidiastole of Cardiovascular Disease

Cardiovascular diseases are the leading cause of death globally; fortunately, 90% of cardiovascular diseases are preventable by long‐term monitoring of physiological signals. Stable, ultralow power consumption, and high‐sensitivity sensors are significant for miniaturized wearable physiological signal monitoring systems. Here, this study proposes a flexible self‐powered ultrasensitive pulse sensor (SUPS) based on triboelectric active sensor with excellent output performance (1.52 V), high peak signal‐noise ratio (45 dB), long‐term performance (10⁷ cycles), and low cost price. Attributed to the crucial features of acquiring easy‐processed pulse waveform, which is consistent with second derivative of signal from conventional pulse sensor, SUPS can be integrated with a bluetooth chip to provide accurate, wireless, and real‐time monitoring of pulse signals of cardiovascular system on a smart phone/PC. Antidiastole of coronary heart disease, atrial septal defect, and atrial fibrillation are made, and the arrhythmia (atrial fibrillation) is indicative diagnosed from health, by characteristic exponent analysis of pulse signals accessed from volunteer patients. This SUPS is expected to be applied in self‐powered, wearable intelligent mobile diagnosis of cardiovascular disease in the future.     

Multifunctional Hybrid Nanoparticles for Traceable Drug Delivery and Intracellular Microenvironment‐Controlled Multistage Drug‐Release in Neurons

Innovative nanoparticles hold promising potential for disease therapy as drug delivery systems. For brain‐disease therapy, a drug delivery system that can sustainably control drug‐release and monitor fluorescence of the drug cargos is highly desirable. In this study, a light‐traceable and intracellular microenvironment‐responsive drug delivery system was developed based on the combination of glutathione‐responsive autoflurescent nanogel, dendrimer‐like mesoporous silica nanoparticles, and gold nanoparticles. The resulting hybrid nanoparticles represent a new class of delivery system that can efficiently load, transport, and control multistage‐release of sulfydryl‐containing drugs into neurons, with light‐traceable monitoring for future brain‐disease therapy.     

Light‐Triggered Biomimetic Nanoerythrocyte for Tumor‐Targeted Lung Metastatic Combination Therapy of Malignant Melanoma

Red blood cell (RBC) membrane‐cloaked nanoparticles, reserving the intact cell membrane structure and membrane protein, can gain excellent cell‐specific functions such as long blood circulation and immune escape, providing a promising therapy nanoplatform for drug delivery. Herein, a novel RBC membrane biomimetic combination therapeutic system with tumor targeting ability is constructed by embedding bovine serum albumin (BSA) encapsulated with 1,2‐diaminocyclohexane‐platinum (II) (DACHPt) and indocyanine green (ICG) in the targeting peptide‐modified erythrocyte membrane (R‐RBC@BPtI) for enhancing tumor internalization and synergetic chemophototherapy. R‐RBC@BPtI displays excellent stability and high encapsulation efficiency with multiple cores enveloped in the membrane. Benefited from the stealth functionality and targeting modification of erythrocyte membranes, R‐RBC@BPtI can significantly promote tumor targeting and cellular uptake. Under the near‐infrared laser stimuli, R‐RBC@BPtI presents remarkable instability by singlet oxygen and heat‐mediated cleavage so as to trigger effective drug release, thereby achieving deep penetration and accumulation of DACHPt and ROS in the tumor site. Consequently, R‐RBC@BPtI with tumor‐specific targeting ability accomplishes remarkable ablation of tumors and suppressed lung metastasis in vivo by photothermal and chemotherapy combined ablation under phototriggering. This research provides a novel strategy of targeted biomimetic nanoplatforms for combined cancer chemotherapy–phototherapy.