Visible light positioning (VLP) is widely believed to be a cost-effective answer to the growing demand for service-based indoor positioning. Meanwhile, high accuracy localization is very important for mobile robots in various scenes including industrial, domestic and public transportation workspace. In this paper, an indoor robot VLP localization system based on Robot Operating System (ROS) is presented for the first time, aiming at promoting the application of VLP in mature robotic system. On the basis of our previous researches, we innovatively designed a VLP localization package which contains the basic operation control of the robots, the features extraction and recognition of the LED-ID, cm-level positioning, and robust dynamic tracking algorithms. This package exploited the proposed lightweight algorithm, distributed framework design, the loose coupling characteristics of the ROS, and the message communication methods among different nodes. What's more, an efficient LED-ID detection scheme is proposed to ensure the lightweight and accuracy of the positioning. A prototype system has been implemented on a Turtlebot3 Robot 1 1 Experiment Demonstration is available at: https://kwanwaipang.github.io/Image/ROS.mp4 . . Experimental results show that the proposed system can provide robot indoor positioning accuracy within 1 cm and an average computational time of only 0.08 s.

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High-Accuracy Robot Indoor Localization Scheme Based on Robot Operating System Using Visible Light Positioning

We report high performance amorphous Indium-Gallium-Zinc-Oxide ( ${a}$ -IGZO) thin-film transis- tors (TFTs) with 10 nm atomic-layer-deposited HfO2 as the gate dielectric, achieving subthreshold swing ( SS ) of 70.2 mV/decade, high effective mobility ( $\mu _{\textit {eff}}$ ) of 55.3cm2/ $\text{V}\cdot \text{s}$ at an inversion carrier density ( $N_{\textit {inv}}$ ) of $5\times 10^{{12}}$ cm-2, and large $I_{ON}/\text{I}_{OFF}$ of >109. Furthermore, very good device-to-device uniformity has been confirmed by the statistical distribution of SS and maximum transconductance (Gm, max) measured from 20 pristine TFT devices. This ${a}$ -IGZO TFT has immense potential for the ultrafast and low power electronic devices for next-generation cost-effective emissive display, image sensing, and hardware for artificial intelligence (AI).

Low Subthreshold Swing and High Mobility Amorphous Indium–Gallium–Zinc-Oxide Thin-Film Transistor With Thin HfO 2 Gate Dielectric and Excellent Uniformity

Ultrafast laser-induced black silicon, from micro-nanostructuring, infrared absorption mechanism, to high performance detecting devices

S-layer protein (SLP) is a surface protein present in many bacteria and shows unique self-assemble ability for various applications, but its detection methods are very limited. In this paper, a label-free, highly selective and sensitive assay of SLP was developed by using the TiO2-coated porous silicon (PSi)-based microfluidic biosensor. The PSi-based biosensor could be easily prepared in a microfluidic device to build a microfluidic biosensing system for measuring SLP in samples rapidly. As the detection principle of the biosensor was based on the light reflection interference, so there was no labeling requirement. The specific recognition capability of the PSi-based biosensor was achieved by the non-covalently immobilized anti-SLP on the PSi surface. The developed biosensing system showed a rapid response time (5 min) and an excellent specificity to SLP, and displayed a broad detection linear range of 0.001 ∼ 10 μg/mL and a low detection limit of 3.2 ± 1.7 × 10−5 μg/mL (0.70 ± 0.37 pM). The microfluidic biosensor can also be used for determination of the apparent dissociation constant (Kd) between SLP and anti-SLP, which was measured to be 4.8 ± 0.9 × 10-9 M.

Rapid and label-free optical assay of S-layer protein with high sensitivity using TiO2-coated porous silicon-based microfluidic biosensor

The threshold voltage (VT) of the AlGaN/GaN HEMT based pH sensor was adjusted by the method of the photoelectrochemical (PEC) oxidation on the GaN cap layer surface. After the PEC oxidation treatments, the VT of the device shifted from -3.46 V to -1.15 V and the gate voltage (VG) corresponding to the maximum transconductance (gmMAX) position (VG|gmMAX) of the device shifted from -2.6 V to -0.1 V. The drain current (ID) variation per pH of the AlGaN/GaN HEMT based pH sensor without reference electrode increased from 0.7 μA to 14 μA when the drain voltage (VD) was 0.5 V. The sensitivity of the reference electrode free AlGaN/GaN HEMT based pH sensor can be significantly increased by regulating the VT to make VG|gmMAX approached the equivalent VG when liquid droplet on the sensing window surface (VG-EQU), which is beneficial to the miniaturization and integration of the AlGaN/GaN HEMT based sensors in the future.

Enhancing the sensitivity of the reference electrode free AlGaN/GaN HEMT based pH sensors by controlling the threshold voltage

Si junction diodes operating in the mode of avalanche breakdown are capable of emitting light in the visible range of 400–900 nm. In this study, to realize the switching speed in the GHz range, we present a transient model to shorten the carrier lifetime in the high electric field region by accumulating carriers in both p and n type regions. We also verify the optoelectronic characteristics by disclosing the related physical mechanisms behind the light emission phenomena. The emission of visible light by a monolithically integrated Si diode under the reverse bias is also discussed. The light is emitted as spatial sources by the defects located at the p–n junction of the reverse-biased diode. The influence of the defects on the electrical behavior is manifested as a current-dependent electroluminescence.

Zhang Ning

Papers

Optoelectronic properties analysis of silicon light-emitting diode monolithically integrated in standard CMOS IC*