DoA Estimation for FMCW Radar by 3D-CNN.

A method of direction-of-arrival (DoA) estimation for FMCW (Frequency Modulated Continuous Wave) radar is presented. In addition to MUSIC, which is the popular high-resolution DoA estimation algorithm, deep learning has recently emerged as a very promising alternative. It is proposed in this paper to use a 3D convolutional neural network (CNN) for DoA estimation. The 3D-CNN extracts from the radar data cube spectrum features of the region of interest (RoI) centered on the potential positions of the targets, thereby capturing the spectrum phase shift information, which corresponds to DoA, along the antenna axis. Finally, the results of simulations and experiments are provided to demonstrate the superior performance, as well as the limitations, of the proposed 3D-CNN.

Self-Powered Pressure Sensor with fully encapsulated 3D printed wavy substrate and highly-aligned piezoelectric fibers array.

Near-field electrospinning (NFES) is capable of precisely deposit one-dimensional (1D) or two-dimensional (2D) highly aligned micro/nano fibers (NMFs) by electrically discharged a polymer solution. In this paper, a new integration of three-dimensional (3D) architectures of NFES electrospun polyvinylidene fluoride (PVDF) NMFs with the 3D printed topologically tailored substrate are demonstrated in a direct-write and in-situ poled manner, called wavy- substrate self-powered sensors (WSS). The fabrication steps are composed of the additive manufacture of 3D printed flexible and sinusoidal wavy substrate, metallization and NFES electrospun fibers in the 3D topology. This 3D architecture is capable of greatly enhancing the piezoelectric output. Finally, the proposed piezoelectrically integrated 3D architecture is applied to the self-powered sensors such as foot pressure measurement, human motion monitoring and finger-induced power generation. The proposed technique demonstrates the advancement of existing electrospinning technologies in constructing 3D structures and several promising applications for biomedical and wearable electronics.

Self-Powered Active Sensor with Concentric Topography of Piezoelectric Fibers.

In this study, we demonstrated a flexible and self-powered sensor based on piezoelectric fibers in the diameter range of nano- and micro-scales. Our work is distinctively different from previous electrospinning research; we fabricated this apparatus precisely via near-field electrospinning which has a spectacular performance to harvest mechanical deformation in arbitrary direction and a novel concentrically circular topography. There are many piezoelectric devices based on electrospinning polymeric fibers. However, the fibers were mostly patterned in parallel lines and they could be actuated in limited direction only. To overcome this predicament, we re-arranged the parallel alignment into concentric circle pattern which made it possible to collect the mechanical energy whenever the deformation is along same axis or not. Despite the change of topography, the output voltage and current could still reach to 5 V and 400 nA, respectively, despite the mechanical deformation was from different direction. This new arbitrarily directional piezoelectric generator with concentrically circular topography (PGCT) allowed the piezoelectric device to harvest more mechanical energy than the one-directional alignment fiber-based devices, and this PGCT could perform even better output which promised more versatile and efficient using as a wearable electronics or sensor.

All-fiber transparent piezoelectric harvester with a cooperatively enhanced structure.

In this paper, we demonstrated a highly-flexible all-fiber based transparent piezoelectric harvester (ATPH) by using the direct-write, near-field electrospinning (NFES) technique and polyvinylidene fluoride (PVDF) micro/nano fibers (MNFs) as source materials. Here, we comprehensively show that transferred high performance transparent electrodes with Au-coated nanowire (NW) electrodes can be obtained using a facile and scalable combined fabrication route of both electrospinning and sputtering processes. Au-coated MNFs of a.c. 110 nm thick can significantly reduce junction resistance, which results in high transmittance (90%) at low sheet resistance (175 Ω sq(-1)). The Au-coated MNFs electrodes also show great flexibility and stretchability, which easily surpass the brittleness of indium tin oxide (ITO) films. Further improvement in ATPH performance was realized by rolling the device into a cylindrical shape, resulting in an increase in power output due to the cooperatively enhanced effect. The rolled ATPH with 0.34 cm diameter produces a high output voltage of ∼4.1 V, current ∼295 nA at a strain of 0.5% and 5 hz. This can efficiently run commercially available electronic components in a self-powered mode without any external electrical supply.

n-Fe2O3 to N⁺-TiO2Heterojunction Photoanode for Photoelectrochemical Water Oxidation.

To improve the performance of the thin hematite photoanode for photoelectrochemical water oxidation, in this work, an nN(+) α-Fe2O3 (hematite)-TiO2 heterojunction photoanode is constructed on fluorine-doped tin oxide substrate to establish a built-in field in the space charge region for facilitating the charge separation in the hematite layer. Charge distribution in the hematite-TiO2 heterostructure is investigated using Kelvin probe force microscopy, which confirms the improvement of charge separation in hematite layer by the formation of energy-matched nN(+) α-Fe2O3-TiO2 heterojunction. Compared to the hematite photoanode, an eightfold enhancement of the photocurrent density at 1.23 V versus reversible hydrogen electrode is measured in the hematite-TiO2 heterojunction photoanode. By using hydrogen peroxide as a hole scavenger, it demonstrates that both charge separation and charge injection efficiencies in the hematite-TiO2 heterojunction photoanode are superior to those in the hematite photoanode. It results from the significant suppressions of the charge recombinations occurring within the hematite layer as well as at the interface of photoelectrode and electrolyte by the formation of the nN(+) α-Fe2O3-TiO2 heterojunction.

mPlum-IFP 1.4 fluorescent fusion protein may display Förster resonance energy transfer associated properties that can be used for near-infrared based reporter gene imaging.

Bacteriophytochrome infrared fluorescent protein (IFP) has a long emission wavelength that is appropriate for detecting pathophysiological effects via near-infrared (NIR) based imaging. However, the brightness and photostability of IFP are suboptimal, although an exogenous supply of biliverdin (BV) IXα is able to enhance these properties. In this study, we fused a far red mPlum fluorescent protein to IFP 1.4 via a linker deoxyribonucleic acid (DNA) sequence encoding eight amino acids. The brightness of mPlum-IFP 1.4 fusion protein at the IFP emission channel was comparable to that of native IFP 1.4 protein when fusion protein and IFP 1.4 were excited by 543 and 633 nm using confocal microscopy, respectively. Visualization of IFP 1.4 fluorescence by excitation of mPlum in mPlum-IFP 1.4 fusion protein is likely to be associated with Förster resonance energy transfer (FRET). The FRET phenomenon was also predicted by acceptor photobleaching using confocal microscopy. Furthermore, the expression of mPlum-IFP 1.4 fusion protein could be detected in cell culture and in xenograft tumors in the absence of BV using in vivo imaging system, although the BV was still essential for detecting native IFP 1.4. Therefore, this innovative-fluorescent fusion protein would be useful for NIR-based imaging in vitro and in vivo.