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

Wireless Monitoring of a Charge Storage in an RF Energy Harvesting Device

Today’s advancements in modern technologies have grown the demand of low power wireless application devices usage. Using the batteries in any portable electronic devices results in a limitation in occupying the space and declining the lifetime of the application devices. Hence, one of the significant challenges in low power wireless technologies is providing the energy sources that are able to supply the required power for operating wireless devices continuously without degrading their performance. Energy harvesting is a growing interest technique to harvest ambient energy from renewable sources such as vibration, solar light, wind, thermal, and electromagnetic wave (EM) and convert these energies into useable electrical energy. Harvesting ambient energy from electromagnetic wave known as the RF energy harvesting is becoming increasingly important for powering the battery-less electronics devices and passive RFID tags. Indeed, this kind of power is readily available especially in HF and UHF frequencies due to the presence of propagating radio waves of wireless technologies such as cellular, TV, radio, satellites, and Wi-Fi signals in environment. Thus, it can be considered as a promising solution to meet the required of the battery replacement and providing a power supply over very long periods. In this project, a radio frequency (RF) energy harvesting unit integrating a passive UHF RFID tag as a charge storage indicator is presented. In this system, an energy harvesting unit converts the RF signal to DC and charges a storage capacitor. In addition, to transfer the maximum power through the system, an impedance matching network is designed between the RF power source and the RF rectifier. The RF switch, consists of a pin diode and UHF RFID tag, monitors the capacitor voltage. When the voltage across the capacitor terminals approaches 0.633 V, signal is transmitted to the RFID reader. The proposed RF energy harvesting system operates at European UHF RFID spectrum from 865.7 MHz to 867.7 MHz, which the frequency of 866 MHz is considered as our target frequency in this study. All the procedure of designing, simulation and fabrication are explained in details and the experimental results indicate that 0.633 V at the terminals of the storage capacitor can be achieved with −5.5 dBm of the RF input power applied into the energy harvesting unit

Equivalent Circuit Approximation to the Connector-Line Transition at High Frequencies using Two Microstrip Lines and Data Fitting

publishedVersionPeer reviewe

Small Triple-Band Meandered PIFA for Brain-Implantable Bio-telemetric Systems : Optimization of Substrate/Superstrate Effectiveness

We optimize and characterize our latest reported small triple-band implantable planar inverted-F antenna (PIFA) resonating at Medical Device Radiocommunication Service (MedRadio) band (401-406 MHz), and Industrial, Scientific, and Medical (ISM) bands (902-928 MHz and 2400-2483.5 MHz) for wireless brain implants. To this end, we used a numerical 7-layer human head model to assess the impact of the substrate and superstrate properties on the peak gain of the antenna. Our results have demonstrated the gain improvements of 2 dB and up to 4.4 dB in the MedRadio and ISM bands, respectively, by optimizing the substrate properties and removing the superstrate.acceptedVersionPeer reviewe

Wireless brain implant for Dopamine monitoring

acceptedVersionPeer reviewe

Wireless Dopamine sensing brain implant: The concept and first results

acceptedVersionPeer reviewe

Antennas and wireless power transfer to small biomedical brain implants

Peer reviewe

Wireless Monitoring of a Charge Storage in an RF Energy Harvesting Device

Today’s advancements in modern technologies have grown the demand of low power wireless application devices usage. Using the batteries in any portable electronic devices results in a limitation in occupying the space and declining the lifetime of the application devices. Hence, one of the significant challenges in low power wireless technologies is providing the energy sources that are able to supply the required power for operating wireless devices continuously without degrading their performance. Energy harvesting is a growing interest technique to harvest ambient energy from renewable sources such as vibration, solar light, wind, thermal, and electromagnetic wave (EM) and convert these energies into useable electrical energy. Harvesting ambient energy from electromagnetic wave known as the RF energy harvesting is becoming increasingly important for powering the battery-less electronics devices and passive RFID tags. Indeed, this kind of power is readily available especially in HF and UHF frequencies due to the presence of propagating radio waves of wireless technologies such as cellular, TV, radio, satellites, and Wi-Fi signals in environment. Thus, it can be considered as a promising solution to meet the required of the battery replacement and providing a power supply over very long periods. In this project, a radio frequency (RF) energy harvesting unit integrating a passive UHF RFID tag as a charge storage indicator is presented. In this system, an energy harvesting unit converts the RF signal to DC and charges a storage capacitor. In addition, to transfer the maximum power through the system, an impedance matching network is designed between the RF power source and the RF rectifier. The RF switch, consists of a pin diode and UHF RFID tag, monitors the capacitor voltage. When the voltage across the capacitor terminals approaches 0.633 V, signal is transmitted to the RFID reader. The proposed RF energy harvesting system operates at European UHF RFID spectrum from 865.7 MHz to 867.7 MHz, which the frequency of 866 MHz is considered as our target frequency in this study. All the procedure of designing, simulation and fabrication are explained in details and the experimental results indicate that 0.633 V at the terminals of the storage capacitor can be achieved with −5.5 dBm of the RF input power applied into the energy harvesting unit

RF energy harvesting system with RFID-enabled charge storage monitoring

Radio frequency (RF) energy scavenging is a compelling approach to energize the low-power wireless devices. We present an energy harvesting system consists of a low-power RF switch circuitry and a passive UHF RFID tag. When the voltage at the storage capacitor terminals exceeds 0.58 V, RF switch connects the UHF RFID microchip to a dipole-type tag antenna. This way, an RFID reader can detect the charge storage level wirelessly with minimal power consumption at the harvester. In this paper, we detail the development of the system and present results from both simulations and measurement. Overall, we were able to achieve 0.58 V at the storage capacitor and detect the storage level indicator tag at the distance of 5.1 m in an experiment where regular 8.7 dBi patch antennas were connected to the harvester input and output of an RFID reader emitting 2.5 W EIRP.acceptedVersionPeer reviewe