Jongman Cho

Application of Wireless Power Transmission Systems in Wireless Capsule Endoscopy: An Overview

Wireless capsule endoscopy (WCE) is a promising technology for direct diagnosis of the entire small bowel to detect lethal diseases, including cancer and obscure gastrointestinal bleeding (OGIB). To improve the quality of diagnosis, some vital specifications of WCE such as image resolution, frame rate and working time need to be improved. Additionally, future multi-functioning robotic capsule endoscopy (RCE) units may utilize advanced features such as active system control over capsule motion, drug delivery systems, semi-surgical tools and biopsy. However, the inclusion of the above advanced features demands additional power that make conventional power source methods impractical. In this regards, wireless power transmission (WPT) system has received attention among researchers to overcome this problem. Systematic reviews on techniques of using WPT for WCE are limited, especially when involving the recent technological advancements. This paper aims to fill that gap by providing a systematic review with emphasis on the aspects related to the amount of transmitted power, the power transmission efficiency, the system stability and patient safety. It is noted that, thus far the development of WPT system for this WCE application is still in initial stage and there is room for improvements, especially involving system efficiency, stability, and the patient safety aspects.

A Portable Automatic Endpoint Detection System for Amplicons of Loop Mediated Isothermal Amplification on Microfluidic Compact Disk Platform

In recent years, many improvements have been made in foodborne pathogen detection methods to reduce the impact of food contamination. Several rapid methods have been developed with biosensor devices to improve the way of performing pathogen detection. This paper presents an automated endpoint detection system for amplicons generated by loop mediated isothermal amplification (LAMP) on a microfluidic compact disk platform. The developed detection system utilizes a monochromatic ultraviolet (UV) emitter for excitation of fluorescent labeled LAMP amplicons and a color sensor to detect the emitted florescence from target. Then it processes the sensor output and displays the detection results on liquid crystal display (LCD). The sensitivity test has been performed with detection limit up to 2.5 × 10−3 ng/µL with different DNA concentrations of Salmonella bacteria. This system allows a rapid and automatic endpoint detection which could lead to the development of a point-of-care diagnosis device for foodborne pathogens detection in a resource-limited environment.

A Fast Center of Pupil Detection Algorithm for VOG-Based Eye Movement Tracking

This paper proposes an algorithm that has been developed for the video-oculograph method. It is used to detect the center of the pupil, extracted from a captured image of an eye acquired by using a CCD camera and a computer with image grabber. The captured eye image is 640 by 480 pixels in size at 8 bits per pixel, in depth. The center of the pupil area could be obtained by applying the proposed algorithms for the threshold of the captured gray-scale image, for image enhancement and noise removing techniques even though the pupil area was partially covered by eyelashes and an eyelid

A study for the hierarchical artificial neural network model for Giemsa-stained human chromosome classification

A hierarchical multi-layer neural network with an error back-propagation training algorithm has been adopted for the automatic classification of Giemsa-stained human chromosomes. The first step classifies chromosomes data into 7 major groups based on their morphological features such as relative length, relative area, centromeric index, and 80 density profiles. The second step classifies each 7 major groups into 24 subgroups using each group classifier. The classification error decreased by using two steps of classification and the classification error was 5.9%. The result of this study shows that a hierarchical multi-layer neural network can be accepted as an automatic human chromosome classifier.

A microdevice for rapid, monoplex and colorimetric detection of foodborne pathogens using a centrifugal microfluidic platform

Outbreaks of foodborne diseases have become a global health concern; hence, many improvements and developments have been made to reduce the risk of food contamination. We developed a centrifugal microfluidic automatic wireless endpoint detection system integrated with loop mediated isothermal amplification (LAMP) for monoplex pathogen detection. Six identical sets were designed on the microfluidic compact disc (CD) to perform 30 genetic analyses of three different species of foodborne pathogens. The consecutive loading, mixing, and aliquoting of the LAMP primers/reagents and DNA sample solutions were accomplished using an optimized square-wave microchannel, metering chambers and revulsion per minute (RPM) control. We tested 24 strains of pathogenic bacteria (Escherichia coli, Salmonella spp and Vibrio cholerae), with 8 strains of each bacterium, and performed DNA amplification on the microfluidic CD for 60min. Then, the amplicons of the LAMP reaction were detected using the calcein colorimetric method and further analysed via the developed electronic system interfaced with Bluetooth wireless technology to transmit the results to a smartphone. The system showed a limit of detection (LOD) of 3 × 10-5ngμL-1 DNA by analysing the colour change when tested with chicken meat spiked with the three pathogenic bacteria. Since the entire process was performed in a fully automated way and was easy to use, our microdevice is suitable for point-of-care (POC) testing with high simplicity, providing affordability and accessibility even to poor, resource-limited settings.

Design and Development of Micro-Power Generating Device for Biomedical Applications of Lab-on-a-Disc.

The development of micro-power generators for centrifugal microfluidic discs enhances the platform as a green point-of-care diagnostic system and eliminates the need for attaching external peripherals to the disc. In this work, we present micro-power generators that harvest energy from the disc’s rotational movement to power biomedical applications on the disc. To implement these ideas, we developed two types of micro-power generators using piezoelectric films and an electromagnetic induction system. The piezoelectric-based generator takes advantage of the film’s vibration during the disc’s rotational motion, whereas the electromagnetic induction-based generator operates on the principle of current generation in stacks of coil exposed to varying magnetic flux. We have successfully demonstrated that at the spinning speed of 800 revolutions per minute (RPM) the piezoelectric film-based generator is able to produce up to 24 microwatts using 6 sets of films and the magnetic induction-based generator is capable of producing up to 125 milliwatts using 6 stacks of coil. As a proof of concept, a custom made localized heating system was constructed to test the capability of the magnetic induction-based generator. The heating system was able to achieve a temperature of 58.62°C at 2200 RPM. This development of lab-on-a-disc micro power generators preserves the portability standards and enhances the future biomedical applications of centrifugal microfluidic platforms.

An algorithm to detect a center of pupil for extraction of point of gaze

This work proposes an algorithm that is developed for the video-oculograph method. It is used to detect a center of pupil for extraction of point of gaze in the eye image acquired by a charge coupled device camera and TV receiver card. The center of pupil could be detected accurately by applying the proposed algorithm in this study that removes noise effectively caused by eyelashes and image that is projected on pupil. In this study, we assume that the pupil is a perfect circle in the captured eye images.

A wireless power transmission system for robotic capsule endoscopy: Design and optimization

This paper presents an inductive coupled wireless power transmission (WPT) system for powering an endoscopic robotic capsule. The proposed WPT system was designed and optimized through manipulation of the core material, the quality factor (Q) and the load impedance matching of the receiving coil (RC). A MnZn ferrite core with high initial permeability was employed. The Q of the 3D RC was optimized by choosing an optimum number of strands and turns. At the optimum design condition the system was able to deliver at least 376 mW of usable power to the load when magnetic field (H-field) of 105 A/m was applied at the frequency of 250 kHz. The uniformity of H-field generated by the power transmitting coil (PTC) was sufficient to achieve 86% stability of received power. The proposed system reduces the required level of H-field by 50% and increases the load power by 22.3% as compared to the existing study.

Stable and High-Efficiency Wireless Power Transfer System for Robotic Capsule Using a Modified Helmholtz Coil

Magnetic resonance-based wireless power transfer system offers a promising solution to overcome power limitations typically encountered by capsule endoscopy. Despite of much attention in this area, aspects such as power stability and power transfer efficiency remain suboptimal and therefore investigation for further improvement is still required. This paper presents a method to improve power stability as well as power transfer efficiency for wireless capsule endoscopy. A new power transmission coil capable of producing uniform magnetic field is proposed to improve power stability through uniform field that at the same time minimizes the unnecessary peak electromagnetic exposure. To improve power transfer efficiency, a mixed resonance scheme is employed. Our experimental results show improvement over existing methods where the proposed system attained power stability of 94.62% and power transfer efficiency of 4.9% under worst position of the receiving coil. Furthermore, the proposed transmitting coil provides additional advantage, where it minimized the unnecessary peak electromagnetic exposure by 26% as compared to the conventional Helmholtz coil-based system. We believe the proposed system will open new direction for future wireless capsule endoscopy and can also be useful in other industrial applications.

An Efficient Gait Phase Detection Device Based on Magnetic Sensor Array

In this paper, we present a prototype of a gait phase detection device which can be used as a part of a gait training and posture correction machine for monoplegia patients. The proposed detection device consists of a magnet shoes and magnetic sensor plate, and it could replace the conventional expensive foot pressure sensors used to detect gait phase. The acquired signal from the magnet shoes and magnetic sensor plate showed good results for the detection of gait phase and could be applied for the gait training and posture correction machine.