Tianjia Sun

A Two-Hop Wireless Power Transfer System With an Efficiency-Enhanced Power Receiver for Motion-Free Capsule Endoscopy Inspection

This paper presents a wireless power transfer system for a motion-free capsule endoscopy inspection. Conventionally, a wireless power transmitter in a specifically designed jacket has to be connected to a strong power source with a long cable. To avoid the power cable and allow patients to walk freely in a room, this paper proposes a two-hop wireless power transfer system. First, power is transferred from a floor to a power relay in the patients jacket via strong coupling. Next, power is delivered from the power relay to the capsule via loose coupling. Besides making patients much more conformable, the proposed techniques eliminate the sources of reliability issues arisen from the moving cable and connectors. In the capsule, it is critical to enhance the power conversion efficiency. This paper develops a switch-mode rectifier (rectifying efficiency of 93.6%) and a power combination circuit (enhances combining efficiency by 18%). Thanks to the two-hop transfer mechanism and the novel circuit techniques, this system is able to transfer an average power of 24 mW and a peak power of 90 mW from the floor to a 13 mm × 27 mm capsule over a distance of 1 m with the maximum dc-to-dc power efficiency of 3.04%.

A new globularity capsule endoscopy system with multi-camera

While wireless endoscopic capsule examining humans large gastrointestinal (GI) cavity, such as stomach and large intestine, it is possible that many interested spots are omitted by the one or two cameras due to its limited field of view. This paper proposes a new globularity capsule endoscopy system with multi-camera. Through analyzing the multi-camera systems optical characteristic and power consumption of the endoscopic capsule system, this paper proposes the spatial physical structure and the electronic architecture of the globularity capsule without blind area. Its diameter can be less than 15mm. The capsule can work in humans GI tract for 8 hours when the image frame rate is 4fps.

An asymmetric resonant coupling wireless power transmission link for Micro-Ball Endoscopy

This paper investigates the design and optimization of a wireless power transmission link targeting Micro-Ball Endoscopy applications. A novel asymmetric resonant coupling structure is proposed to deliver power to an endoscopic Micro-Ball system for image read-out after it is excreted. Such a technology enables many key medical applications with stringent requirements for small system volume and high power delivery efficiency. A prototyping power transmission sub-system of the Micro-Ball system was implemented. It consists of primary coil, middle resonant coil, and cube-like full-direction secondary receiving coils. Our experimental results proved that 200mW of power can be successfully delivered. Such a wireless power transmission capability could satisfy the requirements of the Micro-Ball based endoscopy application. The transmission efficiency is in the range of 41% (worst working condition) to 53% (best working condition). Comparing to conventional structures, Asymmetric Resonant Coupling Structure improves power efficiency by 13%.

Design of Endoscopic Capsule With Multiple Cameras

In order to reduce the miss rate of the wireless capsule endoscopy, in this paper, we propose a new system of the endoscopic capsule with multiple cameras. A master-slave architecture, including an efficient bus architecture and a four level clock management architecture, is applied for the Multiple Cameras Endoscopic Capsule (MCEC). For covering more area of the gastrointestinal tract wall with low power, multiple cameras with a smart image capture strategy, including movement sensitive control and camera selection, are used in the MCEC. To reduce the data transfer bandwidth and power consumption to prolong the MCECs working life, a low complexity image compressor with PSNR 40.7 dB and compression rate 86% is implemented. A chipset is designed and implemented for the MCEC and a six cameras endoscopic capsule prototype is implemented by using the chipset. With the smart image capture strategy, the coverage rate of the MCEC prototype can achieve 98% and its power consumption is only about 7.1 mW.

An efficiency-enhanced wireless power transfer system with segmented transmitting coils for endoscopic capsule

This paper proposes a new wireless power transfer (WPT) system for the endoscopic capsule. In the system, a group of vertically segmented primary coils around the human body are adopted as the transmitting coils. According to the position of the endoscopic capsule, one of the transmitting coils is intelligently selected to transfer the power with the highest efficiency. This paper also presents a coil selection and control algorithm for the unique WPT system. Compared with the conventional design, the calculated transmission efficiencies of the new solution at the best and worst points of the body are enhanced by 53.5% and 138% respectively. And the average efficiency of the proposed solution is about 3.8%.

An omnidirectional wireless power receiving IC with 93.6% efficiency CMOS rectifier and Skipping Booster for implantable bio-microsystems

This paper proposes an omnidirectional wireless power receiving IC for implanted biomedical applications. The IC consists of new power receiving circuits (switch-mode CMOS Rectifier) and new power combination circuits (Skipping Booster). By predicting the coming of the current zero-cross-point (ZCP), the proposed CMOS rectifier switches current with more precise timing. By skipping the rectification in some certain periods, the proposed Skipping Booster combines energy from all rectifiers together. Thanks to the two new circuits, the wireless power receiving IC could receive omnidirectional wireless power with a peak efficiency of 93.6%, which is higher than the conventional results (30%∼80%). It has been verified with a prototype of a batteryless endoscopic capsule.

A new system design of the multi-view Micro-Ball endoscopy system

While the wireless endoscopic capsule examining humans large gastrointestinal (GI) cavity, such as stomach and large intestine, many interested spots are omitted by only one or two cameras due to its limited field of view. This paper proposes the new system architecture of the Micro-Ball for medical endoscopy application. Six cameras are embedded in the Micro-Ball for multiple fields of view, which can reduce endoscopic miss rate greatly. Based on this system architecture, a new working mode is proposed. The captured image data are saved in the Flash memory instead of being transmitted outside human body wirelessly. Only less than 6mJ is consumed when the Micro-Ball captures a frame of 480×480 image and writes the image data into the Flash memory. The endoscopic Micro-Ball can work in humans GI tract for 10 hours when the image frame rate is 2 fps. The Micro-Ball endoscopy system is verified on the FPGA-based demonstration system.

A new omnidirectional wireless power transmission solution for the wireless Endoscopic Micro-Ball

The wireless endoscopic Micro-Ball is used to capture images of gastrointestinal (GI) tracts and save them into Flash memories. The batteries will be exhausted after the Micro-Ball is excreted from human body. So a new wireless power transmission (WPT) solution is proposed to deliver energy from an image reader to the Micro-Ball to fetch the stored images. In this solution, considering that the posture of the Micro-Ball is uncertain when it is placed into the image reader and the volume of the Micro-Ball is too small to contain multiple receiving coils, we employ multiple emitting coils in the image reader and one single receiving coil inside the Micro-Ball. Additionally, an adaptive control mechanism is proposed to select the optimum emitting coil with the highest power efficiency to transmit wireless power to the Micro-Ball placed inside the image reader. As a result, the Micro-Ball can work well in the image reader under all postures with highest power efficiency. The experimental results prove that the power delivering efficiency is in the range of 32% to 36%.

Image registration method for 2D representation of wireless Micro-Ball endoscopic images

Nowadays the interpretation of the images acquired by wireless endoscopy system is a tedious job for doctors. A viable solution is to construct a map, which is a 2D representation of gastrointestinal (GI) tract, based on image registration to reduce the redundancy of images and improve the understandability of them. Nevertheless, the limited field of view makes it difficult for traditional wireless capsule endoscopy system to capture sufficient image information for a complete GI map. The work reported in this paper addresses the problem of the 2D representation of GI tract based on a new wireless Micro-Ball endoscopy system with multiple image sensors. This paper analyses the characteristics of images captured by Micro-Ball endoscopy system and proposes a determination method for registration of wireless endoscopic images based on phase correlation method (PCM). The performance of PCM and the proposed determination method is verified with experiments.

The design and implementation of a chipset for the endoscopic Micro-Ball

A chipset, including one master chip and six same slave chips, is designed and implemented for the endoscopic Micro-Ball, which has six cameras to minimize the blind area while examining the human gastrointestinal (GI) tract. For lowering power consumption, a multi-level clock management for the whole chipset is implemented. A power and area efficient 4 × 4 JPEG image compressor with high image quality is integrated into the slave chip to reduce energy consumption and save FLASH memory space. The master chip and slave chip have been fabricated in 0.18 μm CMOS technology. The experimental results show that the designed chipset for Micro-Ball can support different image frame rates: from 1fps to 6fps with 480×480 image resolution. The power consumption of the chipset is 1.6mW@2fps. The power consumption of the Micro-Ball is estimated about 6mW@2fps. It can work for more than 15 hours, powered by a 1.55V@60mAh battery.