Implantable and Ingestible Antenna Systems: From imagination to realization

Biomedical implantable technologies are life-saving modalities for millions of people globally because of their abilities of wireless remote monitoring, regulating the abnormal functions of internal organs, and early detection of cognitive disorders. Enabling these devices with wireless functionalities, implantable antennas are the crucial front-end component of them. Detailed overviews of the implantable and ingestible antennas, their types, miniaturization techniques, measurement phantoms, biocompatibility issues, and materials are available in the literature. This article comprehensively reviews the design processes, design techniques and methods, types of antennas, electromagnetic (EM) simulators, and radiofrequency (RF) bands used for implantable and ingestible antennas. We briefly discussed the latest advancements in this field and extended their scope beyond conventional implantable applications. Their related issues and challenges are highlighted, and the performance enhancement techniques have been discussed in detail. All the scoped implantable applications have been covered in this review. A standard protocol has been devised to provide a simple and efficient roadmap for the design and realization of the implantable and ingestible antenna for future RF engineers and researchers. This protocol minimizes the errors in simulations and measurements by enhancing the agreement between simulated and measured results and simplifies the process of development of implantable and ingestible antennas. It generalizes the process from idea-to-realization-to-commercialization and provides an easy roadmap for the industry

Implantoitavat paineanturit

Tämä kandidaatintutkielma on kirjallisuustutkimus implantoitavista paineantureista. Tutkielmassa keskitytään implantoitavien paineantureiden perusrakenteeseen ja kahteen yleiseen sovellukseen: kallonsisäisen paineen ja kardiovaskulaarisen paineen mittaamiseen. Implantoitava paineanturi asetetaan osittain tai kokonaan kehon sisälle. Paineanturi rakentuu painetta mittaavasta elementistä, sekä joko johdoista tai langattomasta toteutuksesta, jolla mitatut painearvot saadaan kuljetettua monitorille, lääkäreille analysoitaviksi. Langattomassa toteutuksessa painearvot yleensä lähetetään monitorille joko radioaalloilla tai induktiivisen linkin avulla. Kallonsisäisen paineen mittaaminen on erityisen tärkeää vakavan päähän kohdistuneen vamman jälkeen. Implantoitavilla paineantureilla saadaan tarkempia ja jatkuvia mittaustuloksia, mitkä ovat tärkeitä ominaisuuksia, sillä lääkäreiden on pystyttävä reagoimaan nopeasti mikäli painearvot alkavat kohota. Kardiovaskulaarista painetta mittaavilla implantoivilla paineantureilla tarkastellaan esimerkiksi sydämen toimintaa sydänkammion tukilaitteen asennuksen jälkeen. Lopuksi tutkielma käsittelee biohajoavia implantoitavia paineantureita, jotka tulevat käyttöön tulevaisuudessa. Tällä hetkellä biohajoavat paineanturit ovat testattavana laboratorioissa ja eläinkokeissa. Monet testien tuloksista ovat lupaavia. Biohajoavat implantoitavat paineanturit tiputtavat tulehdusriskiä, sillä ne eivät tarvitse toista leikkausta kuten ei-hajoavat paineanturit, jotka tarvitsevat poistoleikkauksen

An Implantable Low Pressure Biosensor Transponder

The human body’s intracranial pressure (ICP) is a critical element in sustaining healthy blood flow to the brain while allowing adequate volume for brain tissue within the relatively rigid structure of the cranium. Disruptions in the body’s maintenance of intracranial pressure are often caused by hemorrhage, tumors, edema, or excess cerebral spinal fluid resulting in treatments that are estimated to globally cost up to approximately five billion dollars annually. A critical element in the contemporary management of acute head injury, intracranial hemorrhage, stroke, or other conditions resulting in intracranial hypertension, is the real-time monitoring of ICP. Currently such monitoring can only take place short-term within an acute care hospital, is prone to measurement drift, and is comprised of externally tethered pressure sensors that are temporarily implanted into the brain, thus carrying a significant risk of infection. To date, reliable, low drift, completely internalized, long-term ICP monitoring devices remain elusive. In addition to being safer and more reliable in the short-term, such a device would expand the use of ICP monitoring for the management of chronic diseases involving ICP hypertension and further expand research into these disorders. This research studies the current challenges of existing ICP monitoring systems and investigates opportunities for potentially allowing long-term implantable bio-pressure sensing, facilitating possible improvements in treatment strategies. Based upon the research, this thesis evaluates piezo-resistive strain sensing for low power, sub-millimeter of mercury resolution, in application to implantable intracranial pressure sensing

Biomedical technical transfer. Applications of NASA science and technology

Lower body negative pressure testing in cardiac patients has been completed as well as the design and construction of a new leg negative unit for evaluating heart patients. This technology is based on NASA research, using vacuum chambers to stress the cardiovascular system during space flight. Additional laboratory tests of an intracranial pressure transducer, have been conducted. Three new biomedical problems to which NASA technology is applicable are also identified. These are: a communication device for the speech impaired, the NASA development liquid-cooled garment, and miniature force transducers for heart research

Design, realization and measurements of a miniature antenna for implantable wireless communication systems

The design procedure, realization and measurements of an implantable radiator for telemetry applications are presented. First, free space analysis allows the choice of the antenna typology with reduced computation time. Subsequently the antenna, inserted in a body phantom, is designed to take into account all the necessary electronic components, power supply and bio-compatible insulation so as to realize a complete implantable device. The conformal design has suitable dimensions for subcutaneous implantation (10 x 32.1 mm). The effect of different body phantoms is discussed. The radiator works in both the Medical Device Radiocommunication Service (MedRadio, 401-406 MHz) and the Industrial, Scientific and Medical (ISM, 2.4-2.5 GHz) bands. Simulated maximum gains attain and -28.8 and -18.5 dBi in the two desired frequency ranges, respectively, when the radiator is implanted subcutaneously in a homogenous cylindrical body phantom (80 x 110 mm) with muscle equivalent dielectric properties. Three antennas are realized and characterized in order to improve simulation calibration, electromagnetic performance, and to validate the repeatability of the manufacturing process. Measurements are also presented and a good correspondence with theoretical predictions is registered

Implantable antennas for bio-medical applications

Biomedical telemetry has gained a lot of attention with the development in the healthcare industry. This technology has made it feasible to monitor the physiological signs of patient remotely without traditional hospital appointments and follow up routine check-ups. Implantable Medical Devices(IMDs) play an important role to monitor the patients through wireless telemetry. IMDs consist of nodes and implantable sensors in which antenna is a major component. The implantable sensors suffer a lot of limitations. Various factors need to be considered for the implantable sensors such as miniaturization, patient safety, bio-compatibility, low power consumption, lower frequency band of operation and dual-band operation to have a robust and continuous operation. The selection of the antenna is a challenging task in implantable sensor design as it dictates performance of the whole implant. In this paper a critical review on implantable antennas for biomedical applications is presented

Antenna Development in Brain-Implantable Biotelemetric Systems for Next-Generation of Human Healthcare

In the growing efforts of promoting patients’ life quality through health technology solutions, implantable wireless medical devices (IMDs) have been identified as one of the frontrunners. They are bringing compelling wireless solutions for medical diagnosis and treatment through bio-telemetric systems that deliver real-time transmission of in-body physiological data to an external monitoring/control unit. To set up this bidirectional wireless biomedical communication link for the long- term, the IMDs need small and efficient antennas. Designing antenna-enabled biomedical telemetry is a challenging aim, which must fulfill demanding issues and criteria including miniaturization, appropriate radiation performance, bandwidth enhancement, good impedance matching, and biocompatibility. Overcoming the size restriction mainly depends on the resonant frequency of the required applications. Defined frequency bands for biomedical telemetry systems contain the Medical Implant Communication Service (MICS) operating at the frequency band of 402– 405 MHz, Medical Device Radiocommunication Service (MedRadio) resonating at the frequency ranges of 401– 406 MHz, 413 – 419 MHz, 426 – 432 MHz, 438 – 444 MHz, and 451 – 457 MHz, Wireless Medical Telemetry Service (WMTS) operating at frequency specturms of 1395 to 1400 MHz and 1427 to 1432 MHz, and Industrial, Scientific, and Medical (ISM) bands of 433.1–434.8 MHz, 868–868.6 MHz, 902.8–928.0 MHz, and 2.4–2.48 GHz. On the other hand, a single band antenna may not fulfill all requirements of a bio-telemetry system in either MedRadio, WMTS, or ISM bands. As a result, analyzing dual/multi-band implantable antenna supporting wireless power, data transmission, and control signaling can meet the demand for multitasking biotelemetry systems. In addition, among different antenna structures, PIFA has been found a promising type in terms of size-performance balance in lossy human tissues. To overcome the above-mentioned challenges, this thesis, first, starts with a discussion of antenna radiation in a lossy medium, the requirements of implantable antenna development, and numerical modeling of the human head tissues. In the following discussion, we concentrate on approaching a new design for far-field small antennas integrated into brain-implantable biotelemetric systems that provide attractive features for versatile functions in modern medical applications. To this end, we introduce three different implantable antenna structures including a compact dual-band PIFA, a miniature triple-band PIFA and a small quad-band PIFA for brain care applications. The compelling performance of the proposed antennas is analyzed and discussed with simulation results and the triple-band PIFA is evaluated using simulation outcomes compared with the measurement results of the fabricated prototype. Finally, the first concept and platform of in-body and off-body units are proposed for wireless dopamine monitoring as a brain care application. In addition to the main focus of this thesis, in the second stage, we focus on introducing an equivalent circuit model to the electrical connector-line transition. We present a data fitting technique for two transmission lines characterization independent of the dielectric properties of the substrate materials at the ultra-high frequency band (UHF). This approach is a promising solution for the development of wearable and off-body antennas employing textile materials in biomedical telemetry systems. The approach method is assessed with measurement results of several fabricated transmission lines on different substrate materials

Recent Advances on Implantable Wireless Sensor Networks

Implantable electronic devices are undergoing a miniaturization age, becoming more efficient and yet more powerful as well. Biomedical sensors are used to monitor a multitude of physiological parameters, such as glucose levels, blood pressure and neural activity. A group of sensors working together in the human body is the main component of a body area network, which is a wireless sensor network applied to the human body. In this chapter, applications of wireless biomedical sensors are presented, along with state-of-the-art communication and powering mechanisms of these devices. Furthermore, recent integration methods that allow the sensors to become smaller and more suitable for implantation are summarized. For individual sensors to become a body area network (BAN), they must form a network and work together. Issues that must be addressed when developing these networks are detailed and, finally, mobility methods for implanted sensors are presented

A Transcutaneous Data and Power Transfer System for Osteogenesis Monitoring Sensors

Implant devices are widely used in health care applications such as life support systems, patient rehabilitation devices and patient monitoring devices. Medical implants have enabled physicians to obtain relevant real time information regarding an organ, or a site of interest with in the body and suggest treatment accordingly. In some cases, the position of the implant within the body or threats of infections prevents wired communication techniques to extract information from the implant. Wireless communication is the alternative in such cases. Distraction osteogenesis is one such application where wireless communication can be established with callus growth monitoring sensors to obtain bone growth data and activate distraction device. As a solution for wireless communication, the computational design, fabrication and testing of a spiral antenna that can operate in the 401-406 MHz Medical Implant Communication Services (MICS) band is detailed. The proposed system uses ZL70103 MICS band transceiver from Microsemi Corporation and enables wireless communication with the implant. Antenna is tested in an in-vivo system that makes use of biomimetic material and pig femur bone to mimic an application environment. Power requirements for the implant actuator system that performs distraction cannot be satisfied by a single battery. Percutaneous wires for powering the implant poses threats of infection and frequent surgeries for battery replacement alters patient’s immune systems. Wireless charging is viable solution in this case. A short range inductive power transfer system prototype is designed and tested on a custom testbed to analyze the power transfer efficiency with change in distance