With the development of cross-fertilisation in various disciplines, flexible wearable sensing technologies have emerged, bringing together many disciplines, such as biomedicine, materials science, control science, and communication technology. Over the past few years, the development of multiple types of flexible wearable devices that are widely used for the detection of human physiological signals has proven that flexible wearable devices have strong biocompatibility and a great potential for further development. These include electronic skin patches, soft robots, bio-batteries, and personalised medical devices. In this review, we present an updated overview of emerging flexible wearable sensor devices for biomedical applications and a comprehensive summary of the research progress and potential of flexible sensors. First, we describe the selection and fabrication of flexible materials and their excellent electrochemical properties. We evaluate the mechanisms by which these sensor devices work, and then we categorise and compare the unique advantages of a variety of sensor devices from the perspective of in vitro and in vivo sensing, as well as some exciting applications in the human body. Finally, we summarise the opportunities and challenges in the field of flexible wearable devices.

Emissions of carbonaceous aerosols (black carbon [BC] and organic aerosol [OA]) from biomass burning have important climate and human health impacts. Not only the primary emissions are complicated by combustion phases, but also the evolution after emission is not well understood. In this study, single plumes from residential wood burning, extracted from either flaming or smoldering phase, were injected into our novel chamber, to investigate their evolution in real atmospheric conditions with or without solar radiation. Initial compositions of flaming or smoldering plumes were dominated by BC or OA respectively, with higher NO_x emission in flaming. Replicable results showed that in light, smoldering plumes had faster secondary OA (SOA) formation than flaming, due to the higher emissions of volatile organic compounds in smoldering. Furanic and carboxylic acid compounds were found to be the main gaseous precursors and products, respectively. Evaporation and photooxidation concurrently caused increased oxidation in the beginning, but at a later stage of evolution, SOA evolution showed remarkable divergence: enhanced oxidation for smoldering but decreased for flaming plumes, leading to a higher oxygen‐to‐carbon ratio for smoldering than flaming up to 0.25. We found the higher NO_x emission in flaming promoted the gaseous fragmentation reactions, while the seeding particles dominated by OA in smoldering may cause these contrasting tendencies of OA oxidation between combustion phases. Distinct particulate/gas emissions and resultant evolutions in producing SOA at different combustion phases should be therefore considered in evaluating the impacts of biomass burning emissions.

Flexible conformal-enabled antennas have great potential for various developable surface-built unmanned aerial vehicles (UAVs) due to their superior mechanical compliance as well as maintaining excellent electromagnetic features. However, it remains a challenge that the antenna holds bending and thermal insensitivity to negligibly shift resonant frequency during conformal attachment and aerial flight, respectively. Here, we report a flexible symmetric-defection antenna (FSDA) with bending and thermal insensitivity. By engraving a symmetric defection on the reflective ground, the radiated unit attached to the soft polydimethylsiloxane (PDMS) makes the antenna resonate at the ISM microwave band (resonant frequency = 2.44 GHz) and conformal with a miniaturized UAV. The antenna is also insensitive to both the bending-conformal attachment (20 mm < r < 70 mm) and thermal radiation (20~100 °C) due to the symmetric peripheral-current field along the defection and the low-change thermal effect of the PDMS, respectively. Therefore, the antenna in a non-bending state almost keeps the same impedance matching and radiation when it is attached to a cylinder-back of a UAV. The flexible antenna with bending and thermal insensitivity will pave the way for more conformal or wrapping applications.

Dielectrophoresis technology is applied to microfluidic chips to achieve microscopic control of cells. Currently, microfluidic chips based on dielectrophoresis have certain limitations in terms of cell sorting species, in order to explore a microfluidic chip with excellent performance and high versatility. In this paper, we designed a microfluidic chip that can be used for continuous cell sorting, with the structural design of a curved channel and curved double side electrodes. CM factors were calculated for eight human healthy blood cells and cancerous cells using the software MyDEP, the simulation of various blood cells sorting and the simulation of the joule heat effect of the microfluidic chip were completed using the software COMSOL Multiphysics. The effect of voltage and inlet flow velocity on the simulation results was discussed using the control variables method. We found feasible parameters from simulation results under different voltages and inlet flow velocities, and the feasibility of the design was verified from multiple perspectives by measuring cell movement trajectories, cell recovery rate and separation purity. This paper provides a universal method for cell, particle and even protein sorting.

Flexible antennas are widely used in mobile communications, the Internet of Things, personalized medicine, aerospace, and military technologies due to their superior performance in terms of adaptability, impact resistance, high degree of freedom, miniaturization of structures, and cost-effectiveness. With excellent flexibility and portability, these antennas are now being integrated into paper, textiles, and even the human body to withstand the various mechanical stresses of daily life without compromising their performance. The purpose of this paper is to provide a comprehensive overview of the basic principles and current development of flexible antennas, systematically analyze the key performance factors of flexible antennas, such as structure, process, material, and application environment, and then discuss in detail the design structure, material selection, preparation process, and corresponding experimental validation of flexible antennas. Flexible antenna design in mobile communication, wearable devices, biomedical technology, and other fields in recent years has been emphasized. Finally, the development status of flexible antenna technology is summarized, and its future development trend and research direction are proposed.

Periodically tunable nano-gratings have an irreplaceable role in spectral scanning and optical communication, but the performance of gratings manufactured from different materials varies considerably, and the development of superior materials has energized the preparation of high-precision devices. This paper presents a nanoscale preparation process based on Norland Optical Adhesive 73 (NOA73), which enables the rapid preparation of periodically tunable nano-gratings with up to 100% light transmission. The powerful fluidity and shear rate of NOA73 make it uniquely suited to the preparation of precision devices, allowing the production of up to dense grating structures and offering the possibility of making nanoscale gratings. This paper uses multi-angle hierarchical lithography, die stretching, and replication to achieve further improvements in accuracy and successfully prepare gratings with a period of 500 nm. The successful preparation of NOA73 nano-gratings demonstrates the practicality of NOA73 as a material for precision device fabrication.