Energy-Efficient Ingestible Drug Delivery System in the Dynamic Gastrointestinal Environment.

Ingestible electronics are promising platforms for on-demand health monitoring and drug delivery. However, these devices and their actuators must operate in the gastrointestinal (GI) environment, which has a pH range of 1 to 8. Drug delivery systems using electrochemical dissolution of metal films are particularly susceptible to pH changes. Optimal operation in this dynamic environment stands to transform our capacity to help patients across a range of conditions. Here we present an energy-efficient ingestible electronic electrochemical drug delivery system to support subjects through operation in this dynamic environment. The proposed system consists of a drug reservoir sealed with an electrochemically dissolvable gold membrane and an electronic subsystem. An electronic subsystem controls the rate of gold dissolution by sensing and adapting to the pH of the GI environment and provides an option for energy-efficient drug delivery, reducing energy consumption by up to 42.8 %. Integrating the electronics with electrochemical drug delivery enables the proposed system to adapt to the dynamic physiological environments which makes it suitable for drug and/or therapeutic delivery at different locations in the GI tract.

Secure and Stable Wireless Communication for an Ingestible Device.

Wireless communication enables an ingestible device to send sensor information and support external on-demand operation while in the gastrointestinal (GI) tract. However, it is challenging to maintain stable wireless communication with an ingestible device that travels inside the dynamic GI environment as this environment easily detunes the antenna and decreases the antenna gain. In this paper, we propose an air-gap based antenna solution to stabilize the antenna gain inside this dynamic environment. By surrounding a chip antenna with 1 ~ 2 mms of air, the antenna is isolated from the environment, recovering its antenna gain and the received signal strength by 12 dB or more according to our in vitro and in vivo evaluation in swine. The air gap makes margin for the high path loss, enabling stable wireless communication at 2.4 GHz that allows users to easily access their ingestible devices by using mobile devices with Bluetooth Low Energy (BLE). On the other hand, the data sent or received over the wireless medium is vulnerable to being eavesdropped on by nearby devices other than authorized users. Therefore, we also propose a lightweight security protocol. The proposed protocol is implemented in low energy without compromising the security level thanks to the base protocol of symmetric challenge-response and Speck, the cipher that is optimized for software implementation.

Powering Implantable and Ingestible Electronics.

Implantable and ingestible biomedical electronic devices can be useful tools for detecting physiological and pathophysiological signals, and providing treatments that cannot be done externally. However, one major challenge in the development of these devices is the limited lifetime of their power sources. The state-of-the-art of powering technologies for implantable and ingestible electronics is reviewed here. The structure and power requirements of implantable and ingestible biomedical electronics are described to guide the development of powering technologies. These powering technologies include novel batteries that can be used as both power sources and for energy storage, devices that can harvest energy from the human body, and devices that can receive and operate with energy transferred from exogenous sources. Furthermore, potential sources of mechanical, chemical, and electromagnetic energy present around common target locations of implantable and ingestible electronics are thoroughly analyzed; energy harvesting and transfer methods befitting each energy source are also discussed. Developing power sources that are safe, compact, and have high volumetric energy densities is essential for realizing long-term in-body biomedical electronics and for enabling a new era of personalized healthcare.

Surface conduction and electroosmotic flow around charged dielectric pillar arrays in microchannels.

Dielectric microstructures have been reported to have a negative influence on permselective ion transportation because ions do not migrate in areas where the structures are located. However, the structure can promote the transportation if the membrane is confined to a microscopic scale. In such a scale where the area to volume ratio is significantly large, the primary driving mechanisms of the ion transportation transition from electro-convective instability (EOI) to surface conduction (SC) and electroosmotic flow (EOF). Here, we provide rigorous evidence on how the SC and EOF around the dielectric microstructures can accelerate the ion transportation by multi-physics simulations and experimental visualizations. The microstructures further polarize the ion distribution by SC and EOF so that ion carriers can travel to the membrane more efficiently. Furthermore, we verified, for the first time, that the arrangements of microstructures have a critical impact on the ion transportation. While convective flows are isolated in the crystal pillar configuration, the flows show an elongated pattern and create an additional path for ion current in the aligned pillar configuration. Therefore, the fundamental findings of the electrokinetic effects on the dielectric microstructures suggest an innovative application in micro/nanofluidic devices with high mass transport efficiency.

A microrobotic system guided by photoacoustic computed tomography for targeted navigation in intestines in vivo.

Recently, tremendous progress in synthetic micro/nanomotors in diverse environment has been made for potential biomedical applications. However, existing micro/nanomotor platforms are inefficient for deep tissue imaging and motion control in vivo. Here, we present a photoacoustic computed tomography (PACT) guided investigation of micromotors in intestines in vivo. The micromotors enveloped in microcapsules are stable in the stomach and exhibit efficient propulsion in various biofluids once released. The migration of micromotor capsules toward the targeted regions in intestines has been visualized by PACT in real time in vivo. Near-infrared light irradiation induces disintegration of the capsules to release the cargo-loaded micromotors. The intensive propulsion of the micromotors effectively prolongs the retention in intestines. The integration of the newly developed microrobotic system and PACT enables deep imaging and precise control of the micromotors in vivo and promises practical biomedical applications, such as drug delivery.

The Effect of Tele-Health Service on Knowledge and Family support of Hypertension patients / 대한의료정보학회지

OBJECTIVE: The purpose of this study was to evaluate the effect of tele-health service on knowledge and family support of hypertension patients. METHODS: The subjects were two hundred thirty seven primary hypertension patients who were enrolled at health care center located at the cities of Chunchon, Wonju, and Kangreung, Kwangwon-Do. Tele-health system were located health care center of each cities and the service had been provided for three months. Tele-health system called patients every morning to remind them of taking the prescribed medicine by a 12.5 second pre-recorded message. In addition, tele-health system informed the patients of knowledges on hypertension(medication, exercise, nutrition, regular examination) by 18.4 through 25.3 second pre-recorded message during weekend. Data were collected using a questionnaire before and after the service. RESULTS: The differences of knowledge on hypertension before and after tele-health service was significant(t=-7.908, p=.000). Family support before and after the service was statistically significant as well(t=-7.550, p=.000). CONCLUSION: Tele-health service was effective to manage hypertension.