Wireless power transfer system for capsule robot designed by radial square transmitting coil pair with novel ferrite structure.

BACKGROUND: Wireless power transmission for capsule robots has always posed challenges due to the unpredictable postures. METHODS: A radial transmitting coil with a novel ferrite structure is proposed, which consists of two parts with the function of converging magnetic induction lines and reducing magnetic leakage. To improve the flux density, uniformity, and shielding effectiveness, the design parameters are discussed and optimized on the basis of analytical calculations and simulation analysis. RESULTS: The proposed ferrite structure improves the power transfer efficiency from 2.78% to 5.21%. Additionally, the power transfer stability showed a slight improvement from 76.4% to 77.6%, while magnetic leakage was reduced by 84%. Finally, the human tissue safety is also discussed and verified. CONCLUSIONS: The wireless power transfer system is shown to be feasible and safe.

Long-term excessive application of K2SO4 fertilizer alters bacterial community and functional pathway of tobacco-planting soil.

To improve tobacco leaf quality, excessive K2SO4 fertilizers were applied to soils in major tobacco-planting areas in China. However, the effects of K2SO4 application on soil microbial community and functions are still unclear. An eight-year field experiment with three kinds of K2SO4 amounts (low amount, K2O 82.57 kg hm-2, LK; moderate amount, K2O 165.07 kg hm-2, MK; high amount, K2O 247.58 kg hm-2, HK) was established to assess the effects of K2SO4 application on the chemical and bacterial characteristics of tobacco-planting soil using 16S rRNA gene and metagenomic sequencing approaches. Results showed that HK led to lower pH and higher nitrogen (N), potassium (K), sulfur(S) and organic matter contents of the soil than LK. The bacterial community composition of HK was significantly different from those of MK and LK, while these of MK and LK were similar. Compared to LK, HK increased the relative abundance of predicted copiotrophic groups (e.g. Burkholderiaceae, Rhodospirillaceae families and Ellin6067 genus) and potentially beneficial bacteria (e.g. Gemmatimonadetes phylum and Bacillus genus) associated with pathogens and heavy metal resistance, N fixation, dissolution of phosphorus and K. While some oligotrophic taxa (e.g. Acidobacteria phylum) related to carbon, N metabolism exhibited adverse responses to HK. Metagenomic analysis suggested that the improvement of pathways related to carbohydrate metabolism and genetic information processing by HK might be the self-protection mechanism of microorganisms against environmental stress. Besides, the redundancy analysis and variation partitioning analysis showed that soil pH, available K and S were the primary soil factors in shifting the bacterial community and KEGG pathways. This study provides a clear understanding of the responses of soil microbial communities and potential functions to excessive application of K2SO4 in tobacco-planting soil.

Efficient Power Receiving Coil With Novel Ferrite Core Structure for Capsule Robot.

Power receiving coils (PRCs) with ferrite cores are widely used in wireless power transfer (WPT) for capsule robots (CRs) to enhance the power transfer efficiency (PTE). However, due to the large demagnetizing factor, the traditional one-dimensional hollow cylindrical ferrite core has its limitations in volume and performance improvement, which needs to be reconsidered. To this end, we propose a novel PRC equipped with a delicate, lightweight, and more efficient ferrite core structure in this paper. Different from the traditional ferrite core structure, the proposed design composed of distributed ferrite cores and end covers aims to minimize the negative impact of demagnetization on PTE and enhance the magnetic flux concentration. Based on the analysis of the PTE and mutual inductance, influence of the introduced cores on the WPT system is emphasized. The relationship between the change of ferrite core structures and the demagnetizing factors, as well as the effective permeability, is analyzed and simulated. Prototypes of PRCs with different ferrite core configurations are established, tested, and compared to validate the performance enhancement. Experimental results on the power delivered to the load (PDL) and PTE indicate that the proposed design has a volume reduction of 24.4% but performance enhancement of 36% compared with the traditional one with hollow cylindrical ferrite core, thanks to the structure-based demagnetizing factor optimization.

Design and evaluation of perception reconstruction with sensor system for artificial anal sphincter based on vector similarity.

BACKGROUND: Artificial organs are playing an increasingly important role in medical field. Artificial anal sphincter, as an example, is a widely used medical device for fecal incontinence. Though it could help patients maintain continence, the issue of perception reconstruction is still unsolved, which means that patients cannot control defecation as desired. METHODS: In this paper, a novel sensor system based on vector similarity has been analyzed and evaluated. The sensor system is a self-packaged strain gauge sensor with a small size 14.5 mm × 6 mm, especially for medical device implanted in body to reconstruct perception function. In order to overcome the disadvantages of single threshold judgment, a more accurate and reliable judgment standard for content pressure detection in rectum is developed by using vector similarity method. Therefore, in the novel sensor system, standard multi-parameters are comprehensive considered. Furthermore, weight-optimization of sensors are investigated since each sensor has played a different role in detection. Finally, sensor calibration, in vitro and in vivo experiments are established. RESULTS: In sensor calibration, the result R2 > 0.99 presents the strain gauge pressure sensor has a good linearity. After that, a series of in vitro experiments have been conducted. The optimized sensor system shows a high accuracy rate in perception reconstruction, which is 87.5% on early warning and 95% on the alarm. In the following in vivo experiments. The results indicate that the average accuracy of the proposed perception reconstruction module has increased by 17.7%, compared with that without optimized sensor system. CONCLUSIONS: All of these have proven that the novel perception reconstruction module with sensor system based on vector similarity is more acceptable and reliable.

Modelling on mutual inductance of wireless power transfer for capsule endoscopy.

Wireless capsule endoscopy (WCE) is noninvasive, painless, and riskless on detection for gastrointestinal disease. It attracts increasing attention. Wireless power transfer (WPT) technology is utilized to supply power for WCE. Receiving coil (RC) of WPT is capsulated into WCE. Its position and direction change all through gastrointestinal tract. Transmitting coil (TC) is worn by the patient. So the mutual inductance varies all the time. It should be studied to ensure sufficient receiving power. However, existing analytical methods do not reach satisfactory accuracy. They can only solve simple cases with positional misalignment. Numerical simulation models are time-consuming. Furthermore, an entirely new simulation must be repeated when any change in alignment occurs. Thus, based on geometry and misalignment of RC and TC, a model for mutual inductance is proposed. Compared with analytical methods, it is applicable to not only circular and rectangular RC, but also the elliptic, with directional misalignment. It costs below 0.1% of computational time of the simulation for the same accuracy. Moreover, any change in misalignment is easily handled by a simple change of parameter in the model. It reaches a tradeoff between computational accuracy and time. Receiving power is evaluated rapidly and accurately with proposed model.

Enhanced Electrocatalytic Performance of a Porous g-C3 N4 /Graphene Composite as a Counter Electrode for Dye-Sensitized Solar Cells.

A porous graphitic carbon nitride (g-C3 N4 )/graphene composite was prepared by a simple hydrothermal method and explored as the counter electrode of dye-sensitized solar cells (DSCs). The obtained g-C3 N4 /graphene composite was characterized by XRD, SEM, TEM, FTIR spectroscopy, and X-ray photoelectron spectroscopy. The results show that incorporating graphene nanosheets into g-C3 N4 forms a three-dimensional architecture with a high surface area, porous structure, efficient electron-transport network, and fast charge-transfer kinetics at the g-C3 N4 /graphene interfaces. These properties result in more electrocatalytic active sites and facilitate electrolyte diffusion and electron transport in the porous framework. As a result, the as-prepared porous g-C3 N4 /graphene composite exhibits an excellent electrocatalytic activity. In I(-) /I3 (-) redox electrolyte, the charge-transfer resistance of the porous g-C3 N4 /graphene composite electrode is 1.8â€…Ω cm(2) , which is much lower than those of individual g-C3 N4 (70.1â€…Ω cm(2) ) and graphene (32.4â€…Ω cm(2) ) electrodes. This enhanced electrocatalytic performance is beneficial for improving the photovoltaic performance of DSCs. By employing the porous g-C3 N4 /graphene composite as the counter electrode, the DSC achieves a conversion efficiency of 7.13 %. This efficiency is comparable to 7.37 % for a cell with a platinum counter electrode.

[Improvement of Digital Capsule Endoscopy System and Image Interpolation].

Traditional capsule image collects and transmits analog image, with weak anti-interference ability, low frame rate, low resolution. This paper presents a new digital image capsule, which collects and transmits digital image, with frame rate up to 30 frames/sec and pixels resolution of 400 x 400. The image is compressed in the capsule, and is transmitted to the outside of the capsule for decompression and interpolation. A new type of interpolation algorithm is proposed, which is based on the relationship between the image planes, to obtain higher quality colour images. capsule endoscopy, digital image, SCCB protocol, image interpolation

Detection of small bowel tumor based on multi-scale curvelet analysis and fractal technology in capsule endoscopy.

Wireless capsule endoscopy (WCE) has been a revolutionary technique to noninvasively inspect gastrointestinal (GI) tract diseases, especially small bowel tumor. However, it is a tedious task for physicians to examine captured images. To develop a computer-aid diagnosis tool for relieving the huge burden of physicians, the intestinal video data from 89 clinical patients with the indications of potential tumors was analyzed. Out of the 89 patients, 15(16.8%) were diagnosed with small bowel tumor. A novel set of textural features that integrate multi-scale curvelet and fractal technology were proposed to distinguish normal images from tumor images. The second order textural descriptors as well as higher order moments between different color channels were computed from images synthesized by the inverse curvelet transform of the selected scales. Then, a classification approach based on support vector machine (SVM) and genetic algorithm (GA) was further employed to select the optimal feature set and classify the real small bowel images. Extensive comparison experiments validate that the proposed automatic diagnosis scheme achieves a promising tumor classification performance of 97.8% sensitivity and 96.7% specificity in the selected images from our clinical data.

A complexity-efficient and one-pass image compression algorithm for wireless capsule endoscopy.

BACKGROUND: As an important part of the application-specific integrated circuit (ASIC) in wireless capsule endoscopy (WCE), the efficient compressor is crucial for image transmission and power consumption. OBJECTIVE: In this paper, a complexity-efficient and one-pass image compression method is proposed for WCE with Bayer format images. The algorithm is modified from the standard lossless algorithm (JPEG-LS). METHODS: Firstly, a causal interpolation is used to acquire the context template of a current pixel to be encoded, thus determining different encoding modes. Secondly, a gradient predictor, instead of the median predictor, is designed to improve the accuracy of the predictions. Thirdly, the gradient context is quantized to obtain the context index (Q). Eventually, the encoding process is achieved in different modes. RESULTS: The experimental and comparative results show that our proposed near-lossless compression method provides a high compression rate (2.315) and a high image quality (46.31 dB) compared with other methods. CONCLUSION: It performs well in the designed wireless capsule system and could be applied in other image fields.

[A method for bleeding detection in endoscopy images using SVM].

Because the huge number of images of the digestive tract by Wireless Capsule Endoscopy (WCE) are left to the medical personnels detected by their eyes, huge burden leaves to doctors. This article provides a classification of method based on SVM (Support Vector Machine) for the capsule endoscopy bleeding intelligent recognition. We created a new kind of feature parameter, and the experiment result can reach 83% specificity and 94% sensitivity.

Dual-head wireless powered video capsule based on new type of receiving coils.

Wireless capsule endoscopy (WCE) has been a great breakthrough in visually detecting the pathological changes of gastrointestinal (GI) wall, but the limit of viewing angle and power by batteries still hinder the wide application of WCE. In order to address these shortcomings, a dual-head video capsule system based on new type of receiving coils is presented. First, the dual-head video capsule system is designed, which could capture images of the whole GI tract in two channels, transforming the images into NTSC videos at a frame rate of 30 f s(-1) and transmitting the signals outside the body. Second, the wireless power transmission platform with new type of receiving coils is established to provide at least 108 mW of continuous, stable energy for the capsule. Then a prototype was fabricated and applied in animal experiments. The designed dual-head video capsule system is proved to be feasible and a potential solution for future clinical application.