Smart garments for monitoring physiological and biomechanical signals of the human body are key sensors for personalized healthcare. However, they typically require bulky battery packs or have to be ...plugged into an electric plug in order to operate. Thus, a smart shirt that can extract energy from human body motions to run body-worn healthcare sensors is particularly desirable. Here, we demonstrated a metal-free fiber-based generator (FBG) via a simple, cost-effective method by using commodity cotton threads, a polytetrafluoroethylene aqueous suspension, and carbon nanotubes as source materials. The FBGs can convert biomechanical motions/vibration energy into electricity utilizing the electrostatic effect with an average output power density of ∼0.1 μW/cm2 and have been identified as an effective building element for a power shirt to trigger a wireless body temperature sensor system. Furthermore, the FBG was demonstrated as a self-powered active sensor to quantitatively detect human motion.
Over the past few years, the rapid development of tactile sensing technology has contributed significantly to the realization of intuitional touch control and intelligent human-machine interaction. ...Apart from physical touch or pressure sensing, proximity sensing as a complementary function can extend the detection mode of common single functional tactile sensors. In this work, we present a transparent, matrix-structure dual functional capacitive sensor which integrates the capability of proximity and pressure sensing in one device, and the excellent spatial resolution offered by the isolated response of capacitive pixels enables us to realize precise location identification of approaching objects and loaded pressure with fast response, high stability and high reversibility.
Self‐powered and wearable electronics, which are away from the problems of batteries, can provide the sustainable and comfortable interactive service for people. In this work, cellular polypropylene ...piezoelectret, which is with excellent physical and electrical properties, is utilized to build the human body energy harvesting and self‐powered human health monitoring systems. The cellular polypropylene piezoelectret flexible generator can reach a maximum peak power density of ≈52.8 mW m−2. Simultaneously, self‐powered human body biological signals detecting sensors are demonstrated to detect the human physiological signals, such as coughing action and arterial pulses. This study strongly indicates the great compatibility and potential applications in human healthy monitoring may pave a new developing way for portable and wearable electronics systems.
Simple‐structured and efficient human body energy harvesting and self‐powered human health monitoring systems are demonstrated basing on the cellular polypropylene piezoelectret. A maximum peak power density of ≈52.8 mW m−2 is obtained and human physiological signals, such as coughing action and arterial pulse, are detected. These systems develop a new way for self‐powered and wearable electronics.
Flexible all‐solid‐state asymmetric supercapacitors (ASCs) are fabricated from a novel anode – WO3–x/MoO3–x core/shell nanowires on carbon fabric – and a polyaniline cathode (figure). In addition to ...the high electrochemical performance of the devices, other characteristics, such as low toxicity, flexibility, environmental compatibility, light weight, and low requirements for packaging, make the all‐solid‐state ASCs potential candidates for applications in energy storage, flexible electronics, and other consumer electronics.
The cellular piezoelectret generator (CPG) has drawn considerable attention as an emerging flexible energy harvester because of its advantages of a simple structure, easy assembly, a low cost, and ...eco‐friendliness. To facilitate practical applications, an initial theoretical study of CPGs is presented in this work, in which the output characteristics of CPGs can be optimized through an appropriate choice of parameters, including the electret dielectric permittivity, device structure, polarization process, and external load. A good agreement with experimental results is achieved, verifying the validity of the theoretical study. The reported theory offers a complete interpretation of the dynamic working mechanism of CPGs and provides significant guidance for the design of a CPG with enhanced yield.
A theoretical study of cellular piezoelectret generators (CPGs) is presented, focusing on the enhancement of their dynamic performance. An effective means to optimize the output characteristics of CPGs is found. This discovery will enhance performance and application range of future devices.
Metasurface holograms, with the capability to manipulate spatial light amplitudes and phases, are considered next-generation solutions for holographic imaging. However, conventional fabrication ...approaches for meta-atoms are heavily dependent on electron-beam lithography (EBL), a technique known for its expensive and time-consuming nature. In this paper, a polarization-insensitive metasurface hologram is proposed using a cost-effective and rapid nanoimprinting method with titanium dioxide (TiO2) nanoparticle loaded polymer (NLP). Based on a simulation, it has been found that, despite a reduction in the aspect ratio of meta-atoms of nearly 20%, which is beneficial to silicon master etching, NLP filling, and the mold release processes, imaging efficiency can go up to 54% at wavelength of 532 nm. In addition, it demonstrates acceptable imaging quality at wavelengths of 473 and 671 nm. Moreover, the influence of fabrication errors and nanoimprinting material degradation in terms of residual layer thickness, meta-atom loss or fracture, thermal-induced dimensional variation, non-uniform distribution of TiO2 particles, etc., on the performance is investigated. The simulation results indicate that the proposed device exhibits a high tolerance to these defects, proving its applicability and robustness in practice.
A metasurface is a layer of subwavelength-scale nanostructures that can be used to design functional devices in ultrathin form. Various metasurface-based optical devices – coined as flat optics ...devices – have been realized with distinction performances in research laboratories using electron beam lithography. To make such devices mass producible at low cost, metasurfaces over a large area have also been defined with lithography steppers and scanners, which are commonly used in semiconductor foundries. This work reviews the metasurface process platforms and functional devices fabricated using complementary metal-oxide-semiconductor-compatible mass manufacturing technologies. Taking both fine critical dimension and mass production into account, the platforms developed at the Institute of Microelectronics (IME), A*STAR using advanced 12-inch immersion lithography have been presented with details, including process flow and demonstrated optical functionalities. These developed platforms aim to drive the flat optics from lab to fab.
In the trend of spectrometer miniaturization, the design of combining computational imaging with the metasurfaces has been proved to be an efficient and feasible solution. Nevertheless, determining ...the optimal filter array design remains a compelling subject for ongoing research. A computational microspectrometer consisting of a planar array of broadband optical filters is proposed, which are formed by low-loss freeform dielectric metasurfaces. Diverse metasurface designs are obtained by using binary graph generation technology, and rich spectral responses are obtained. The final performance of microspectrometer depends on the trade-offs between reconstruction time, relative error, footprint, and resolution. To optimize these trade-offs, we have improved the existing freeform metasurface design scheme and optimized the filter array design. Simulation results show the proposed microspectrometer can successfully reconstruct the spectra over the 380 to 680 nm spectral range with a resolution of 1 nm. In summary, we propose an integrated design including meta-pixel design, filter combinations and simulation test flow, which leads to an impressive performance microspectrometer.
Compared with conventional lenses, metalenses can offer smaller form factor, light weight and new functionality, and have become the focus of the recent investigations of metasurface. To date, quite ...a lot of studies have been reported for chromatic aberration correction of metalenses. Noting most work was carried out to satisfy the required group delay or dispersion by introducing sophisticated and integrated nanopillars, which are obtained using computationally intensive global search algorithms. Generally, the design is time-consuming. Here, we propose an alternative scheme, where metalens that corrects the chromatic aberration can be designed by optimizing the spectral degree of freedom C(ω), rather than relying on time-consuming algorithms. The proposed metalens is compatible with the complementary metal oxide semiconductor (CMOS) fabrication process. The numerically demonstrated metalens with a diameter of 200 μm and a numerical aperture (NA) of 0.24 has a small focal length fractional change (FLFC) of 4.1% over the wavelength of 9 ∼ 12 μm with an average efficiency of 51.7% in transmission mode. Moreover, the effect of fabrication deviations on the performance of the metalens is analyzed, showing critical dimension (CD) bias, sidewall angle and pillar height all have different levels of influence on the performance of the metalens.
Metalenses made of artificial sub-wavelength nanostructures have shown the capability of light focusing and imaging with a miniaturized size. Here, we report the demonstration of mass-producible ...amorphous silicon metalenses on a 12-inch glass wafer via the complementary metal-oxide-semiconductor compatible process. The measured numerical aperture of the fabricated metalens is 0.496 with a focusing spot size of 1.26 μm at the wavelength of 940 nm. The metalens is applied in an imaging system to test the imaging resolution. The minimum bar of the resolution chart with a width of 2.19 μm is clearly observed. Furthermore, the same system demonstrates the imaging of a fingerprint, and proofs the concept of using metalens array to reduce the system size for future compact consumer electronics.
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