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Polymer-based nanocomposites emerged in the 1960s as a groundbreaking approach to advanced materials. By incorporating robust, durable, and multifunctional nanomaterials into a polymer matrix, the performance of nanocomposites has significantly surpassed that of the base polymers. However, over the past six decades, the challenges of achieving uniform nanomaterial dispersion and the resulting non-uniform properties have impeded further progress in this field. Here, we present a polymer-based nanocomposite with highly dispersed nanomaterials, achieved through aerosol-jet-based multi-material three-dimensional (AM3D) printing. This method allows precise programming of the nanocomposite's composition, structure, and dispersity. Numerical simulations in the design of AM3D printing system facilitate the avoidance of interfacial compatibility issue among heterogeneous aerosols, enabling distributed printing without nanomaterial agglomeration. As a result of this high level of dispersion and distribution, the 3D structured nanocomposite exhibits a uniform dielectric constant and low dielectric loss across the entire printed area. This work establishes an engineering framework for defect-free nanocomposites and significantly expands the range of polymer-based multi-material nanocomposite that can be designed and manufactured with complex architectures. Aerosol-jet-based multi-material 3D printing enables highly dispersed nanomaterials in the polymer-based nanocomposite. [Display omitted] • Brief but intensive review regarding the conventional nanocomposite fabrication methods. • Invention of a novel nanocomposite fabrication method. • Rigorous validation of the degree of dispersion. • Demonstration of the efficacy of newly developed nanocomposite. [ABSTRACT FROM AUTHOR]

Abstract Recently, flutter-driven triboelectric nanogenerator (TENG) has shown huge potential in wind energy harvesting from ambient environments. However, almost all the reported devices are based on parallel structure which suffers from a critical problem of insufficient contact between triboelectric surfaces. In this work, we propose an angle-shaped TENG (AS-TENG) with the above issue resolved. The device is based on two Al layers stacked to form an angle shape and a FEP film positioned in between by sharing a common side. Thanks to this design, the FEP film can contact fully and intimately with the Al layers to facilitate the effect of contact electrification and electrostatic induction. Compared with the existing parallel-structured TENG, the AS-TENG shows an overwhelming output performance because of the enhanced contact area. Furthermore, the AS-TENG is introduced a wedge-shaped wind guide channel which can provide a driving force for the flutter and hence lower the start-up wind speed largely. To further enhance the electric output, the AS-TENGs can be facilely integrated into a 360° radial array, showing an enlarged windward area and a high level of integration. The AS-TENG array can be applied to harvest outdoor weak wind and act as a direct power source to charge a capacitor or drive electronic devices. This work provides a design strategy for natural weak wind scavenging which may push forward the practical applications of TENG for wind power. Graphical abstract fx1 Highlights • An AS-TENG has been demonstrated and shows enhanced performance in comparison with the reported parallel-structured devices. • A wedge-shaped wind guide channel is introduced to facilitate the flutter and hence lower the start-up wind speed largely. • The AS-TENG can be facilely integrated into a 360° radial array for efficiently harvesting natural weak wind outdoors. [ABSTRACT FROM AUTHOR]

Face masks are key personal protective equipment for reducing exposure to viruses and other environmental hazards such as air pollution. Integrating flexible and wearable sensors into face masks can provide valuable insights into personal and public health. The advantages that a breath-monitoring face mask requires, including multi-functional sensing ability and continuous, long-term dynamic breathing process monitoring, have been underdeveloped to date. Here, we design an effective human breath monitoring face mask based on a flexible La 0.7 Sr 0.3 MnO 3 (LSMO)/Mica respiration sensor. The sensor's capabilities and systematic measurements are investigated under two application scenes, namely clinical monitoring mode and daily monitoring mode, to monitor, recognise, and analyse different human breath status, i.e. , cough, normal breath, and deep breath. This sensing system exhibits super-stability and multi-modal capabilities in continuous and long-time monitoring of the human breath. We determine that during monitoring human breath, thermal diffusion in LSMO is responsible for the change of resistance in flexible LSMO/Mica sensor. Both simulated and experimental results demonstrate good discernibility of the flexible LSMO/Mica sensor operating at different breath status. Our work opens a route for the design of novel flexible and wearable electronic devices. [Display omitted] • Flexible La 0.7 Sr 0.3 MnO 3 /Mica respiration sensor shows super-stability and multi-modal capabilities. • Thermal diffusion is responsible for the change of resistance. • Flexible La 0.7 Sr 0.3 MnO 3 /Mica respiration sensor can operate at different breath modes. [ABSTRACT FROM AUTHOR]

Contact electrification is coupled with electrostatic induction in developing triboelectric nanogenerator as a new energy technology. The triboelectric nanogenerator has two basic operating modes that can be used to harvest a variety of mechanical energy. It provides not only a viable means of powering portable and wearable electronics, but also demonstrates a possible route towards power generation in large scale. This paper makes a comprehensive review on fundamentals, operating modes, device design and performance enhancement of this newly emerged technology. [ABSTRACT FROM AUTHOR]

We present a newly designed self-powered identification system based on sliding electrification by combination of a barcode fabricated by gratings with intervals of different widths between each other and a reader consists of a layer of FEP film and a strip electrode. Introducing a reference interval and a baseline, an encoding method was established by calculating the ratio of time spent for sliding across the strip electrode and the one for the reference interval. Sliding across a reader at a constant speed rate from 10 mm/s to 100 mm/s, even swiping a card by human hands, coded information by gratings with intervals of different widths was successfully identified. This work demonstrates the practicability of a self-powered, triboelectric-based identification system, and indicates its potential applications in laboratories, libraries, and industry. [ABSTRACT FROM AUTHOR]

A practical self-powered velocity sensor based on the principles of a triboelectric generator for either rectified linear or rotary motion is presented. The effort represents the first successful attempt in integrating a triboelectric generator into a commercial digital circuit for the dual-mode speed sensing. Employing alternating Kapton-copper strips arranged in a spiral configuration wrapped on the inner and outer surfaces of two concentric cylinders, voltage assays for linear and rotary motions can be measured without the need for an external power source. The triboelectric generated output signals when integrated with a digital circuit and a microcontroller unit can be directly processed into remarkably stable, macro-scale output signals for measurements of (0.1−0.6) ms −1 ±0.5% for linear velocities and (300−700) rpm±0.9% for rotary velocities. We have also discussed the measuring sensitivities and limitations of our device in the paper. We believe our pioneering demonstration of the applied triboelectric technology will have a huge impact in the industrial commercialization of self-powered devices and sensors. [ABSTRACT FROM AUTHOR]

Abstract: New technologies that can scavenge ambient environmental energy have attracted increasing interest in the past decades. Recently, triboelectric nanogenerator (TENG) has been demonstrated as a powerful approach for harvesting various forms of mechanical energies. In this work, a newly designed TENG is demonstrated by coaxially integrating multiple layers disk TENGs into a whole system, which transforms the fluid flow into rotation motion of multiple layers disks and generates a multiplied electrical output. To achieve the effective structural integration and output multiplication, a D-shape shaft is adopted to facilitate the synchronized relative rotation of all the segmentally-structured disk layers and light weight and low stiffness springs are employed to ensure the intimate contact of the tribo-surfaces. With the above design, the nanogenerator delivers an open-circuit voltage up to ~470V and a short-circuit current density of 90.6mA/m2, corresponding to an instantaneous maximum power density of 42.6W/m2 (2.68kW/m3) at a rotation speed of 1000rpm. By combining the TENG with a water turbine, the device can be effectively driven by a water flow from a common household faucet. This technology represents an important advance of TENGs toward practical applications and shows great potential in hydroelectric power and wind power industries. [Copyright &y& Elsevier]

Coronavirus disease 2019 (COVID-19) as a severe acute respiratory syndrome infection has spread rapidly across the world since its emergence in 2019 and drastically altered our way of life. Patients who have recovered from COVID-19 may still face persisting respiratory damage from the virus, necessitating long-term supervision after discharge to closely assess pulmonary function during rehabilitation. Therefore, developing portable spirometers for pulmonary function tests is of great significance for convenient home-based monitoring during recovery. Here, we propose a wireless, portable pulmonary function monitor for rehabilitation care after COVID-19. It is composed of a breath-to-electrical (BTE) sensor, a signal processing circuit, and a Bluetooth communication unit. The BTE sensor, with a compact size and light weight of 2.5 cm3 and 1.8 g respectively, is capable of converting respiratory biomechanical motions into considerable electrical signals. The output signal stability is greater than 93% under 35%–81% humidity, which allows for ideal expiration airflow sensing. Through a wireless communication circuit system, the signals can be received by a mobile terminal and processed into important physiological parameters, such as forced expiratory volume in 1 s (FEV 1) and forced vital capacity (FVC). The FEV 1 /FVC ratio is then calculated to further evaluate pulmonary function of testers. Through these measurement methods, the acquired pulmonary function parameters are shown to exhibit high accuracy (>97%) in comparison to a commercial spirometer. The practical design of the self-powered flow spirometer presents a low-cost and convenient method for pulmonary function monitoring during rehabilitation from COVID-19. • We develop a low-cost and convenient method for pulmonary function monitoring during rehabilitation from COVID-19. • It is composed of a lightweight breath-to-electrical sensor, a signal processing circuit, and a Bluetooth communication unit. • The output signal stability is greater than 93% under 35%–81% humidity, which allows for ideal expiration airflow sensing. • A wireless communication system receives signals from a mobile terminal and converts them into pulmonary parameters. • The FEV1/FVC ratio is then calculated to further evaluate pulmonary function of testers with high accuracy of >97%. [ABSTRACT FROM AUTHOR]

[Display omitted] • Additively manufactured conformable microfluidic force sensor to measure forces during joint replacement. • Quantitative force data from sensors could aid precise implant positioning and balance. • Sensor design optimised using finite element modelling and calibrated within a 3D printed model hip implant. • High sensitivity demonstrated at typical forces experienced during hip replacements. • Powerful new surgical tool to aid implant positioning, increasing the lifetime of hip replacements. Balancing forces within weight-bearing joints such as the hip during joint replacement is essential for implant longevity. Minimising implant failure and the corresponding need for expensive and difficult revision surgery is vital to both improve the quality of life of the patient and lighten the burden on overstretched healthcare systems. However, balancing forces during total hip replacements is currently subjective and entirely dependent on surgical skill, as there are no sensors currently on the market that are capable of providing quantitative force feedback within the small and complex geometry of the hip joint. Here, we solve this unmet clinical need by presenting a thin and conformable microfluidic force sensor, which is compatible with the standard surgical procedure. The sensors are fabricated via additive manufacturing, using a combination of 3D and aerosol-jet printing. We optimised the design using finite element modelling, then incorporated and calibrated our sensors in a 3D printed model hip implant. Using a bespoke testing rig, we demonstrated high sensitivity at typical forces experienced following implantation of hip replacements. We anticipate that these sensors will aid soft tissue balancing and implant positioning, thereby increasing the longevity of hip replacements. These sensors thus represent a powerful new surgical tool for a range of orthopaedic procedures where balancing forces is crucial. [ABSTRACT FROM AUTHOR]