Tae Song Kim

First clinical trial of the “MiRo” capsule endoscope by using a novel transmission technology: electric-field propagation

BACKGROUNDnWe developed a capsule endoscope (CE), MiRo, with the novel transmission technology of electric-field propagation. The technology uses the human body as a conductive medium for data transmission. Specifications of the prototype include the ability to receive real-time images; size, 10.8 x 24 mm; weight, 3.3 g; field of view, 150 degrees; resolution of power, 320 x 320 pixels; and transmittal speed, 2 frames per second.nnnOBJECTIVEnTo evaluate the clinical safety and diagnostic feasibility of the prototype MiRo, we conducted a multicenter clinical trial.nnnDESIGN AND PATIENTSnAll volunteers underwent baseline examinations, including EGD and electrocardiography for the screening of GI obstructive and cardiovascular diseases, before the trial. In the first 10 cases, 24-hour Holter monitoring was also performed. To evaluate the diagnostic feasibility, transmission rate of the captured images, inspection rate of the entire small bowel, and quality of transmitted images (graded as outstanding, excellent, good/average, below average, and poor) were analyzed.nnnRESULTSnOf the 49 healthy volunteers, 45 were included in the trial, and 4 were excluded because of baseline abnormalities. No adverse effects were noted. All CEs were expelled within 2 days, and the entire small bowel could be explored in all cases. The transmission rates of the captured image in the stomach, small bowel, and colon were 99.5%, 99.6%, and 97.2%, respectively. The mean total duration of image transmission was 9 hours, 51 minutes, and the mean transit time of the entire small bowel was 4 hours, 33 minutes. Image quality was graded as good or better in 41 cases (91.1%). Details of the villi and vascular structures of the entire small bowel were clearly visualized in 31 cases (68.9%).nnnCONCLUSIONSnMiRo is safe and effective for exploring the entire small bowel, with good image quality and real-time feasibility. This novel transmission technology may have applications beyond the field of capsule endoscopy.

Active locomotion of a paddling-based capsule endoscope in an in vitro and in vivo experiment (with videos)

BACKGROUNDnCapsule endoscopy that could actively move and approach a specific site might be more valuable for the diagnosis or treatment of GI diseases.nnnOBJECTIVEnWe tested the performance of active locomotion of a novel wired capsule endoscope with a paddling-based locomotion mechanism, using 3 models: a silicone tube, an extracted porcine colon, and a living pig.nnnDESIGNnIn vitro, ex vivo, and in vivo experiments in a pig model.nnnSETTINGnStudy in an animal laboratory.nnnINTERVENTIONSnFor the in vitro test, the locomotive capsule was controlled to actively move from one side of a silicone tube to the other by a controller-operated automatic traveling program. The velocity was calculated by following a video recording. We performed ex vivo tests by using an extracted porcine colon in the same manner we performed the in vitro test. In in vivo experiments, the capsule was inserted into the rectum of a living pig under anesthesia, and was controlled to move automatically forward. After 8 consecutive trials, the velocity was calculated.nnnMAIN OUTCOME MEASUREMENTSnElapsed time, velocity, and mucosal damage.nnnRESULTSnThe locomotive capsule showed stable and active movement inside the lumen both in vitro and ex vivo. The velocity was 60 cm/min in the silicone tube, and 36.8 and 37.5 cm/min in the extracted porcine colon. In the in vivo experiments, the capsule stably moved forward inside the colon of a living pig without any serious complications. The mean velocity was 17 cm/min over 40 cm length. We noted pinpoint erythematous mucosal injuries in the colon.nnnLIMITATIONnPorcine model experiments, wired capsule endoscope.nnnCONCLUSIONSnThe novel paddling-based locomotive capsule endoscope performed fast and stable movement in a living pig colon with consistent velocity. Further investigation is necessary for practical use in humans.

Micro Capsule Endoscope for Gastro Intestinal Tract

A novel capsule endoscope (CE) named MiRo was developed based on a completely new transmission technology known as electric-field propagation. This technology marks the initial achievement of cooperative research between the Intelligent Microsystem Center of KIST, IntroMedic Co., Ltd, and Yonsei University College of Medicine under Koreas Frontier 21 project. The specifications of MiRo include real-time image receiving, 10.8 times 24 mm, 3.3 g, 320 times 320 pixel formats, 3 frame/sec, and over 11 hours of battery time.

Autonomous locomotion of capsule endoscope in gastrointestinal tract

Autonomous locomotion in gastrointestinal (GI) tracts is achieved with a paddling-based capsule endoscope. For this, a miniaturized encoder module was developed utilizing a MEMS fabrication technology to monitor the position of paddles. The integrated encoder module yielded the high resolution of 0.0025 mm in the linear motion of the paddles. In addition, a PID control method was implemented on a DSP to control the stroke of the paddles accurately. As a result, the average accuracy and the standard deviation were measured to be 0.037 mm and 0.025 mm by a laser position sensor for the repetitive measurements. The locomotive performance was evaluated via ex-vivo tests according to various strokes in paddling. In an in-vivo experiment with a living pig, the locomotion speed was improved by 58% compared with the previous control method relying on a given timer value for reciprocation of the paddles. Finally, the integrated encoder module and the control system allow consistent paddling during locomotion even under loads in GI tract. It provides the autonomous locomotion without intervention in monitoring and controlling the capsule endoscope.

Improvement of locomotive performance of capsular microrobot moving in GI tract using position based feedback control

The position based feedback control system is proposed in order to improve the locomotive performance of the paddling based capsular microrobot moving in gastrointestinal (GI) tracts. The miniaturized optical encoder is designed and fabricated for the positional feedback of the mobile in the microrobot, which results in the precise positioning with the resolution of 0.1 mm. Moreover, the stroke of the mobile is optimized to increase the forwarding velocity of the microrobot. The control performance is verified by comparing the targeted displacement with the measured one under various loading conditions. The velocity of the microrobot is evaluated according to the various strokes and driving voltages under visco-elastically deformable and rare deformable conditions. The control system works properly with high resolution and accuracy and the velocity of the microrobot is maximized under the optimized stroke. In the in-vitro test, the velocity of the microrobot controlled by the position based feedback is increased by 73 % when the optimized stroke is applied, compared with the velocity by the time based control.

Micromachined ultrasound transducer array for cell stimulation with high spatial resolution

In this work, we present a piezoelectric micromachined ultrasonic transducer (pMUT) array for local stimulation on cultured cells with a high spatial resolution for the first time. We used a bulk piezoelectric film that has a higher piezoelectric coefficient (d31) than that of the thin film materials to achieve high acoustic power within a small membrane. The 500-μm-wide and 55-μm-thick transducer membrane exhibits a resonant frequency of 780 kHz, which is within the effective frequency range for stimulating cells. We also demonstrate successful in vitro experiments by stimulating cells using the fabricated pMUT array and verifying the stimulation using fluorescence calcium imaging. Using fluorescence imaging, we observed an increase in Ca2+ level of TRPA1 expressing HEK293T cells under ultrasound sonication, which confirms that TRPA1 channel in HEK293T cells was activated by ultrasound.