Wireless Medical Telemetry Service Research Articles

Conformal wideband ingestible capsule MIMO antenna system for multi-channel communication in biotelemetry

This article presents the design of a compact conformal multiple-input-multiple-output (MIMO) capsule antenna aimed at enabling robust communication and high data rates over a broad frequency range spanning from 0.3 to 2.5 GHz. This range encompasses essential frequency bands such as medical implant communications services (MICS) (401–406 MHz), wireless medical telemetry services (WMTS) (1.4 GHz), and industrial, scientific, and medical (ISM) (0.433 GHz, 0.915 GHz, and 2.45 GHz) for wireless capsule biotelemetry. The size of the capsule is reduced to 17 mm × 7 mm (typically 26 mm × 11 mm) to ensure the safe passage of the capsule without being trapped inside the intestine. The proposed antenna (integrated with dummy electronics to build a fully encased capsule endoscope design) is placed inside homogeneous and heterogeneous phantoms in the simulation. The antenna prototype is fabricated, and performance metrics are measured by implanting it inside pork meat and phantom solution. The proposed MIMO antenna offers a wide impedance bandwidth of ∼2200 MHz, and the measured isolation between the antenna elements is > 20 dB. The proposed antenna is also tested for robustness (interaction between the electronic components and the endoscope’s antenna) and human safety using system considerations and realistic voxel models.

Designing a Compact Dual-Band, Dual-Polarized Antenna for Biotelemetry Communications Using the Characteristic Mode Method.

A compact dual-band, dual-polarized, implantable antenna was designed using the characteristic mode method for operation in the wireless medical telemetry service (WMTS) band (1.4 GHz) and the industrial, scientific, and medical (ISM) band (2.45 GHz). By utilizing slotting techniques and materials with high dielectric constants, the antenna volume was minimized to 47.4 mm3, and circular polarization was gained in the WMTS band by using the characteristic mode method. A three-layer physical model of human tissues was constructed in a simulation, and a biogel and minced pork were used in the measurements. The measured peak gains are -20.85 dBi (1.4 GHz) and -22.15 dBi (2.45 GHz). The measured effective axis ratio bandwidth in the WMTS band is 170 MHz (1.33-1.50 GHz, 12.0%), and the impedance bandwidth in the ISM band is 390 MHz (2.21-2.60 GHz, 16.2%). At 1.4 GHz and 2.45 GHz, the largest 1 g average SAR values are 376 W/Kg and 318 W/Kg, which comply with IEEE C95.1-1999. Moreover, when the communication chain affinity exceeds 20 dB for 1.4 GHz and 2.4 GHz, the transceiver range reaches 8.2 m and 9.7 m. This antenna can be used for implantable wireless telemetry systems.

A Triple-Band Broadband Miniature Antenna Design for Implantable Continuous Glucose Monitoring

This paper presents a miniaturized triband implantable planar antenna that covers the industrial, scientific, and medical (ISM) band and the Wireless Medical Telemetry Service (WMTS) band which can be used in a continuous blood glucose monitoring device. The antenna consists of a slotted radiating patch and a ground plane with a cross slot to miniaturize its size. The overall antenna size is only 51.35 mm3 (7.6 × 7.6 × 0.889 mm3) due to the reduced size by the slotting technique. Compared to other implantable antennas with similar performance, the proposed antenna is smaller in size, simple in construction, and easy to be fabricated. By cutting a cross slot in GND, impedance matching is improved, especially at the two higher frequency bands. We have fabricated the prototype and carried out measurements. The results show its gains are −32.2 dBi, −18.8 dBi, and −19.1 dBi at 0.9 GHz, 1.4 GHz, and 2.45 GHz, respectively. Its radiation patterns have good symmetry in the two lower operating frequency bands. In addition, the maximum SAR values comply with the IEEE standard safety guidelines (IEEE C95.1-2019).

A dual wide-band ingestible antenna design for wireless capsule endoscopy

In this paper, we present a dual wide-band ingestible antenna design for wireless capsule endoscopy (WCE) biotelemetry applications. The design process employs Characteristic Mode Analysis (CMA) and driven modal analysis. The effectiveness of the prototype antenna is afterward assessed through measurements using a tissue-equivalent phantom liquid model. We investigate the effects of antenna implantation depth and capsule shell thickness on its performance, providing insights into practical considerations. The proposed dual-band antenna demonstrates good performance in both the 1.4 GHz Wireless Medical Telemetry Services (WMTS) and 2.45 GHz Industrial, Scientific, and Medical (ISM) bands, exhibiting measured impedance bandwidths of 36% and 22%, respectively. The measured peak realized gains are −22.9 dBi and −25.3 dBi for the WMTS and ISM bands, respectively, with a compact footprint of 78.5 mm2. To ensure health and safety and optimal performance, we evaluate the antenna's specific absorption rate (SAR) and link margin (LM). Additionally, we assess the performance of the proposed antenna in comparison with the state-of-the-art design for capsule antennas in WCE applications.

A Miniaturized Tri-Band Implantable Antenna for ISM/WMTS/Lower UWB/Wi-Fi Frequencies.

This study aims to design a compact antenna structure suitable for implantable devices, with a broad frequency range covering various bands such as the Industrial Scientific and Medical band (868-868.6 MHz, 902-928 MHz, 5.725-5.875 GHz), the Wireless Medical Telemetry Service (WMTS) band, a subset of the unlicensed 3.5-4.5 GHz ultra-wideband (UWB) that is free of interference, and various Wi-Fi spectra (3.6 GHz, 4.9 GHz, 5 GHz, 5.9 GHz, 6 GHz). The antenna supports both low and high frequencies for efficient data transfer and is compatible with various communication technologies. The antenna features an asynchronous-meandered radiator, a parasitic patch, and an open-ended square ring-shaped ground plane. The antenna is deployed deep inside the muscle layer of a rectangular phantom below the skin and fat layer at a depth of 7 mm for numerical simulation. Furthermore, the antenna is deployed in a cylindrical phantom and bent to check the suitability for different organs. A prototype of the antenna is created, and its reflection coefficient and radiation patterns are measured in fresh pork tissue. The proposed antenna is considered a suitable candidate for implantable technology compared to other designs reported in the literature. It can be observed that the proposed antenna in this study has the smallest volume (75 mm3) and widest bandwidth (181.8% for 0.86 GHz, 9.58% for 1.43 GHz, and 285.7% for the UWB subset and Wi-Fi). It also has the highest gain (-26 dBi for ISM, -14 dBi for WMTS, and -14.2 dBi for UWB subset and Wi-Fi) compared to other antennas in the literature. In addition, the SAR values for the proposed antenna are well below the safety limits prescribed by IEEE Std C95.1-1999, with SAR values of 0.409 W/Kg for 0.8 GHz, 0.534 W/Kg for 1.43 GHz, 0.529 W/Kg for 3.5 GHz, and 0.665 W/Kg for 5.5 GHz when the applied input power is 10 mW. Overall, the proposed antenna in this study demonstrates superior performance compared to existing tri-band implantable antennas in terms of size, bandwidth, gain, and SAR values.

Compact Wideband Implanted Antenna for Medical Device Radiocommunications Service, Long Term Evolution, Global System for Mobile Communications, and Wireless Medical Telemetry Service Band Biosensing Applications

Compact Wideband Implanted Antenna for Medical Device Radiocommunications Service, Long Term Evolution, Global System for Mobile Communications, and Wireless Medical Telemetry Service Band Biosensing Applications

A Miniaturized Implantable Antenna for Wireless Power Transfer and Communication in Biomedical Applications

A miniaturized, triple-band, implantable antenna for biomedical applications is presented in this paper. The proposed antenna with dimensions of 8.1 mm × 8.1 mm × 0.64 mm, combined with a shorting pin and a ground slot, operates at bands between 401–406 MHz for the medical implant communications service (MICS); 1,395–1,400 MHz and 1,427–1,432 MHz for the wireless medical telemetry service (WMTS); and 2,400–2,500 MHz for industrial, scientific, and medical (ISM) applications. The antenna is deployed simultaneously for data transmission and wireless power transfer (WPT) at the two frequencies of communications and the ISM band, respectively. The antenna achieves peak gain values of -35.7 dBi, -25.1 dBi, and -19.5 dBi with the impedance bandwidths of 10.1%, 15.5%, and 9.58% at 402 MHz, 1.4 GHz, and 2.45 GHz, respectively. The experiments in the muscle tissue were implemented to demonstrate the reliability of the proposed antenna. To ensure safety standards in the human body environment, the specific absorption rate (SAR) value is simulated and evaluated thoroughly.

An Ultra-Miniaturized Antenna With Ultra-Wide Bandwidth for Future Cardiac Leadless Pacemaker

The detuning owing to the complex in-body operating scenarios, environmental factors, and circuitry of the implantable medical devices (IMDs) are the primary concerns in integrating implantable antennas with their corresponding systems. The wide bandwidth achievement for avoiding the detuning challenges is constrained by device specifications and antenna miniaturization. This study presents an ultra-miniaturized antenna of only 10.66 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> volume with an ultra-wide bandwidth of 3040 MHz (0.79–3.83 GHz) for a leadless pacemaker (LP). The proposed antenna encompasses the five important bands: ISM (868–868.6 MHz, 902–928 MHz, and 2.4–2.48 GHz), Wireless Medical Telemetry Service (WMTS) (1395–1400 MHz), and the midfield (1.45–1.6 GHz) bands. To consider a practical operating scenario, the antenna was integrated with a battery and controlling electronics of an LP. In a homogeneous heart phantom (HHP), the proposed antenna showed a higher gain of −28.7, −20.02, and −16.7 dBi at 915 MHz, 1.4 GHz, and 2.45 GHz, respectively. The specific absorption rate (SAR) evaluation in the heart of a realistic model guaranteed patient safety by satisfying the IEEE C95.1-2005 and C95.1-1999 guidelines. The antenna is experimentally validated through measurements in minced pork. The strength of the received signal in the measurements confirms a stable biotelemetric link of the proposed ultra-wideband (UWB) antenna with an external monitoring system. The results obtained through simulations and in vitro testing emphasized that the proposed ultra-miniaturized and UWB antenna could operate more efficiently in the heart, thus establishing itself as a suitable candidate for the LPs.

A Novel Wideband and Multi-band Implantable Antenna Design for Biomedical Telemetry

In this work, a novel multi-tracks wideband and multi-band miniaturized antenna design for implanted medical devices biomedical telemetry is proposed. This antenna entirely covers seven frequency bands which are the bands (401−406) MHz of the Medical Device Radiocommunications Service (MedRadio), the three bands (433.1−434.8), (868.0−868.6), and (902.8−928.0) MHz of the Industrial, Scientific, and Medical (ISM), and the three bands (608−614) MHz, and (1.395−1.400) and (1.427−1.432) GHz of the Wireless Medical Telemetry Service (WMTS). The antenna possesses a compact full size of (19.5 × 12.9 × 0.456) mm3. The antenna miniaturization and impedance bandwidth enhancement are achieved using two techniques: the patch slotting and insertion of open-end slots in the ground plane, respectively. Prototype of proposed antenna with multi-tracks has been fabricated and tested in free space. The comparison between the simulated and measured reflection coefficient has been done and found in good agreement with each other. Furthermore, simulations of the proposed antenna implanted in the underneath the scalp in a realistic human model shows a wideband operation from 0.19 to 0.94 GHz, and from 1.38 to 1.54 GHz corresponding to return loss (S11 ≤ −10 dB). Link budget calculation is performed to specify the range of telemetry considering both Specific Absorption Rate (SAR) restrictions and effective isotropic radiated power (EIRP) limitations. The designed implantable antenna with full ground plane presents an appropriate reflection coefficient for muscle implantation. Furthermore, the designed implanted muscle antenna may be also suitable for skin implantation.

Design and implementation of compact dual-band conformal antenna for leadless cardiac pacemaker system

The leadless cardiac pacemaker is a pioneering device for heart patients. Its rising success requires the design of compact implantable antennas. In this paper, we describe a circularly polarized Hilbert curve inspired loop antenna. The proposed antenna works in the WMTS (Wireless Medical Telemetry Services) 1.4 GHz and ISM (Industrial, Scientific, and Medical) 2.45 GHz bands. High dielectric constant material Rogers RT/Duroid 6010 LM ({epsilon }_{r}=10) and fractal geometry helps to design the antenna with a small footprint of 9.1 mm3 (6 mm × 6 mm × 0.254 mm). The designed antenna has a conformal shape that fits inside a leadless pacemaker’s capsule is surrounded by IC models and battery, which are tightly packed in the device enclosure. Subsequently, the integrated prototype is simulated deep inside at the center of the multi-layer canonical heart model. To verify experimentally, we have put dummy electronics (IC and battery) inside the 3D printed pacemaker’s capsule and surfaced the fabricated conformal antenna around the inner curved body of the TCP (Transcatheter Pacing) capsule. Furthermore, we have tested the TCP capsule by inserting it in a ballistic gel phantom and minced pork. The measured impedance bandwidths at 1.4 GHz and 2.45 GHz are 250 MHz and 430 MHz, whereas measured gains are − 33.2 dBi, and − 28.5 dBi, respectively.

A compact implantable MIMO antenna with high isolation and wide bandwidth

ABSTRACT A compact wideband three-unit implantable multiple-in-multiple-out (MIMO) antenna for biomedical applications is proposed in this paper. By loading a “Y” slots on the radiation patch, and a metallized via between the radiation patch and the ground plane, they are jointly designed to reduce the Q value of the antenna unit and improve its bandwidth. At same time, three “wolf-teeth club “ slots with filtering characteristics are introduced into the ground plane to isolate the coupling of ground surface current at feed ports of antenna units, so as to improve the isolation between feed ports. The 10 dB bandwidth of the MIMO antenna unit is 1.21 GHz-1.66 GHz, covering the commonly used Wireless Medical Telemetry Services (WMTS) band (1.427–1.432 GHz). And the isolation between units is more than 29 dB in the whole 450 MHz bandwidth, among which the isolation in WMTS band are more than 31 dB. Compared with other implantable MIMO antennas, this design not only integrates more MIMO antenna units in a small area but also each MIMO unit has broadband characteristics.

医用テレメータ受信機で発生する相互変調に関する研究

Passive intermodulation may generate when two signals are input in the receiver and is an issue that threatens wireless communications. It has been recommended that medical facilities operating wireless medical telemetry services should be conduct zone management for avoiding the effect of passive intermodulation. In this study, the occurrence frequency of passive intermodulation in a wireless medical telemetry service was investigated using simulated environment. Passive intermodulation occurred when two input signal levels were high and frequency deviation of two signals were narrow. The amplitude of passive intermodulation depends on the input signal level in which near its frequency. Passive intermodulation effected the reception of wireless medical telemetry services and degraded carrier to noise ratio as 2 to 4 dB worse rather than Gaussian noise. The signal level of wireless medical telemetry service coming from another floor has no potential to cause passive intermodulation by conducting zone management as properly. However, the output power of wireless communication devices that using same frequency of wireless medical telemetry services such as telecontrol devices is generally greater (10 mW). When the introduction of these devices, it would be desirable for clinical settings to conduct prepare zone management to avoiding passive intermodulation.

Estimation of Electromagnetic Environment of Wireless Medical Telemetry Services Using Machine Learning

In this study, we developed the novel machine learning model to estimate electromagnetic environment of wireless medical telemetry services (WMTS) using In-phase / Quadrature phase data (I/Q data) of normal and interfered its signals. If the occurrence of electromagnetic interference (EMI) sources and carrier to noise ratio (CNR) can be estimated automatically, the management of electromagnetic environment of WMTS can be easier. We, therefore, proposed the machine learning method for estimating an occurrence of EMI and calculating CNR. As the results of the performance evaluation by Stratified K-Fold cross-validation on 74 types of recorded I/Q data, an occurrence of EMI was predicted with 97.6% accuracy by AdaBoost classifier. Whether the CNR was more than 30 dB was predicted with 95.6% accuracy by decision tree classifier. In addition, this method classified 4 CNR levels such as < 20 dB, 20 to 30 dB, 30 to 40 dB, and 40 dB ≦ with 90.5% accuracy by random forest classifier. Moreover, CNR was estimated with 99.5% R-square and 0.661 dB mean absolute error by K-Fold cross-validation using gradient boosting regression tree. Our method is effective for investigating electromagnetic environments in clinical settings.

A Compact Wideband Flexible Antenna for Wireless Medical Telemetry Services

A Compact Wideband Flexible Antenna for Wireless Medical Telemetry Services

A Symmetrical Closed-Loop Conformal Antenna With Wideband for Capsule Endoscope

A symmetrical closed-loop conformal antenna is designed for capsule endoscope at wireless medical telemetry service (608–614 MHz) band and industrial, scientific, and medical (902–918 MHz and 2.4–2.4835 GHz) band. The antenna is compartmentalized into two loops with an inverted-Ω loop and a hollow-T loop by the differential feeding. The antenna has a wideband (| <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> | < −10 dB) covering 0.47–1.14 GHz and 1.38–3 GHz. The omnidirectional radiation pattern of the antenna is verified by measurement, and the peak gains are (−15.5, −16.8, and −23.1) dBi for the (611, 915, and 2400) MHz designs, respectively. The antenna possesses excellent environmental tolerance <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in vivo</i> environment test. Moreover, the specific absorption rate value of the antenna can satisfy the IEEE regulations under the limit of 2.42 mW net-input power.

Multiband antenna design based on Gosper fractal for implantable biomedical devices

AbstractIn this paper, a novel multiband implantable planar inverted-F antenna (PIFA) antenna based on Gosper curve fractal geometry is designed for biomedical telemetry applications. The antenna has covered four dedicated frequency bands; medical implant communication system band (MICS 402–405 MHz), industrial, scientific, and medical bands (ISM 902–928 MHz and 2.4–2.5 GHz), and wireless medical telemetry services (WMTS 1395–1400 and 1429–1432 MHz). The proposed antenna is designed on Rogers RO 3010 substrate of thickness 25 mil and volume equal to 153.67 mm3. The reflection coefficient and the radiation pattern are measured inside muscle-mimicking liquid tissue phantom. The antenna has achieved the impedance bandwidth of 126, 406, 168, and 175 MHz at MICS (403 MHz), ISM (915 MHz), WMTS (1400 MHz), and ISM (2.45 GHz) with maximum gain value −33.6, −21.04, −15.48, and −10.25 dBi, respectively. The data link range between the implantable antenna and off body antenna has been performed with −16 dBm input power. Additionally, the obtained specific absorption rate with the input of 25 μW power has also been obtained within the safety limit and hence ensures the reliability of the proposed antenna.

Ultra-wideband Flexible Implantable Antenna for Wireless Capsule Endoscopy System with Performance Improvement

The implantable antenna is an important part of the wireless capsule endoscopy (WCE) system to achieve wireless communication. This paper designed an ultra-wideband flexible implantable antenna for wireless capsule endoscopy system. With a very wide bandwidth, the antenna can completely cover the industrial, scientific, and medical frequency bands (ISM, 2.4-2.48 GHz) and Wireless Medical Telemetry Service (WMTS, 1.395-1.4 GHz). The expanded size of the proposed antenna is 18mm× 10mm× 0.1mm. The conformal technology of the antenna has further reduced the space of the system and achieved miniaturization. The capsule antenna in this paper is a compact planar monopole antenna fed by a coplanar waveguide, and it uses a flexible material as a dielectric substrate to achieve the conformal shape of the antenna. U-shaped ground branch (UGB) and a loaded split ring resonator (SRR) structure were used to further improve the antenna performance. Simulation and measurement results were basically the same. On the premise of radiation safety and miniaturization of the antenna, the ultra-wideband operation of the antenna was realized. This antenna design provided reference value for the design and application of the capsule antenna.

Path Loss Models for Wireless Cardiac RF Communication

In this letter, we propose fundamental path loss (PL) models which play vital roles in promoting the intraheart communication system design of future deeply implanted leadless pacemakers inside the cardiac chambers. Initially, employing a plane wave approach yields the attenuation of the electric field in homogeneous heart tissue, while a modified Friis equation in the lossy medium is utilized to evaluate the power transmission between transmitting and receiving antennas in homogeneous heart tissue in the far-field zone. An Hertzian dipole excitation is used to separate the mismatch and ohmic losses of the antenna from the path loss in an anatomical human body simulation environment. Based on this theoretical and full-wave simulation setup, PL models are derived and comprehensively compared at different potential frequency bands [Medical Implant Communication Service (MICS) 402-405 MHz, Wireless Medical Telemetry Service (WMTS) 608-614 MHz, Industrial, Scientific, and Medical (ISM) 867-869 MHz, and 2400-2500 MHz], and the validity of applying the Friis equation in this scenario is verified.

A Low Complex Spectrum Sensing Technique for Medical Telemetry System

Wearable wireless sensors play a vital role in healthcare applications to transfer information of patients. Generally, wearable devices are used for monitoring, diagnosing, and treating various medical conditions. In this paper authors propose a novel energy detection scheme for spectrum allotment to a medical telemetry network. So, we proposed cognitive radio technology to dynamically utilize Wireless Medical Telemetry Services (WMTS). By using Medical body area networks, we can improve remote patient monitoring as well as facilitating immediate response from the service provider. Further, we also outline the challenges of implementing spectrum sensing for body sensor networks. In this paper, spectrum sensing using energy detection can be used for implementing medical telemetry in healthcare applications. The proposed Normalized Median Least Mean Square (NMLMS) algorithm with sign regressor operation also solves the problem of complexity of circuit in basic spectrum sensing using energy detection phenomenon. The experimental results show that performance of NMLMS gives better performance in terms of convergence of the health care system. The probability of detection of a spectrum are demonstrated at various false alarm rates as 0.025, 0.05, and 0.1 and signal to noise ratio from -10 dB to 0 dB.

A Compact Triple-Band Antenna With a Broadside Radiation Characteristic for Head-Implantable Wireless Communications

This letter presents a compact triple-band antenna composed of a spiral radiator with an open-ended slot at the ground for human head-implantable wireless communications. It operates simultaneously at a Medical Implant Communications Service (MICS) band (402-405 MHz), a Wireless Medical Telemetry Service (WMTS) band (1427-1432 MHz), and an Industrial, Scientific, and Medical (ISM) band (2400-2480 MHz). The proposed antenna has a thin profile of 0.5 mm with a volume of 197 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . Semisolid phantoms are used for the design and experimental validation, and detailed parameter studies are carried out to determine the working principles of the antenna. Based on simulations and measurements, it was found that the proposed antenna covers all the desired frequency bands with comparably high boresight gains given its compact dimensions.