Medical Implant Communication Service Research Articles

Comparison of Passive 2-D and 3-D Ring Arrays for Medical Telemetry Focusing

In this letter, we investigate the performance of subdermal ring designs for focusing electromagnetic fields inside the body for next-generation implantable medical devices. We will concentrate on the Medical Implant Communications Service band $(\text{402} \text{--}\text{405 MHz})$ , but prepare our design at $\text{433 MHz}$ , the nearest Industrial, Scientific, Medical band. The designs include two-dimensional (2-D or coplanar) and 3-D arrays of circular rings and 3-D arrays of ellipses. The 3-D ring and ellipse arrays focus the fields more effectively than 2-D designs, through constructive coupling between the rings. Compared to the case where no rings are used, the power available from the focused field 20 mm below the skin is 2.24 times and 3.12 times larger if 3-D rings and 3-D ellipses are utilized, respectively. Rings can be used for circular polarization applications, and ellipses are more optimal for linear polarization applications.

A compact dual‐band implantable antenna for medical telemetry

AbstractWe present the design of a planar, low‐profile dual‐band implantable antenna which operates in the 402‐ to 405‐MHz Medical Implant Communication Service (MICS) and the 2.4‐ to 2.5‐GHz Industrial, Scientific, and Medical (ISM) bands. The designed antenna was experimentally validated by implanting it first into a synthetic human skin tissue phantom and then a minced pork model. The measurement results show that the antenna has 10‐dB impedance bandwidths of at least 120 MHz which covers the MICS band and at least 40 MHz which covers the ISM band. The proposed antenna is printed on an RO3210 substrate and it occupies a compact volume of 22 mm × 16 mm × 1.27 mm. The average SAR values at the center frequency of both bands, that is, 403.5 MHz and 2.45 GHz are, respectively, below 0.352 and 0.054 μW/kg. Both values are far below the limits stipulated by the IEEE C95.1‐1999 (ie, 1.6 W/kg) and IEEE C95.1‐2005 (ie, 2 W/kg) standards. The simulated and measured performance of the antenna confirms its good radiation characteristics.

A dual‐band case‐printed planar inverted‐F antenna design with independent resonance control for wearable short range telemetric systems

In this article, a novel 3D meandered planar inverted-F antenna (PIFA) is proposed for dual band application targeting Wireless Body Area Network (WBAN). The proposed antenna is printed on the casing of a 3D-base-station model having a size of 88 × 95 × 10.2 mm3. The proposed PIFA covers two bands including medical implant communication service (MICS) (402-405 MHz), as well as the industrial, scientific, and medical (ISM) (2.4-2.48 GHz) bands. Each of the two bands can be controlled independently. The 3D configuration contains two linked meandered resonators to downsize the structure. Due to its conformal shape, omnidirectional radiation pattern, and low-profile nature, the proposed PIFA is a potential candidate for targeting the WBAN applications. The proposed antenna, covering the MICS and ISM bands, works with an optimally matching (VSWR<2) at the aforementioned bands. The design concept was validated by fabricating the antenna prototype and measuring its characteristics.

A dual‐band implantable antenna with wide‐band characteristics at MICS and ISM bands

AbstractThis letter presents the design of a miniaturized dual‐band spiral antenna for biomedical applications. The recommended antenna covers both the Medical Implant Communication Service MICS (402‐405 MHz) as well as the Industrial Scientific Medical ISM (2.4‐2.48 GHz) band. Different size reduction techniques have been applied to downsize the antenna and the latter achieved a compact size of 14 × 17 × 0.25 mm3. For validation purpose, measurements were conducted in the saline solution having properties comparable to muscles. The structure achieves very good measured peak gain values of −33 dBi and − 16 dBi at 403 MHz and 2.45 GHz, respectively. The proposed antenna has a wide‐band characteristic at both bands, which is the key for an antenna to be implanted into different tissue environments. Both the simulated and measured impedance bandwidths are sufficiently covering the intended bands. A decent agreement is observed between simulated and measured results.

A Highly-Integrated Low-Noise MICS Band Receiver RF Front-End IC with AC-Coupled Current Mirror Amplifier

This work presents a low-noise, low-power receiver RF front-end integrated circuit (IC) for 402–405[Formula: see text]MHz medical implant communications service (MICS) band applications using 0.18-[Formula: see text]m CMOS process. The proposed front-end employs an AC-coupled current mirroring amplifier in between the low-noise current-reuse transconductor amplifier and a single-balanced IQ mixer for improved gain and noise performance in comparison to previous works. The designed front-end IC achieves a simulated performance of 36.5[Formula: see text]dB conversion gain, 1.85[Formula: see text]dB noise figure, and IIP3 of [Formula: see text][Formula: see text]dBm while consuming 440[Formula: see text][Formula: see text]W from 1-V voltage supply. The consumed core layout area, including I/Q LO generation and current bias circuits, is only 0.29[Formula: see text]mm2.

Design of a printed symmetrical CPW-fed monopole antenna for on-body medical diagnosis applications

A printed symmetric co-planar waveguide (CPW)-fed on-body monopole antenna is proposed for use on human arm body phantoms in medical diagnosis applications. The advantages of the presented antenna over other on-body antennas include low profile, miniaturization, wide bandwidth, and lower reflection coefficient, with good peak gain and better impedance matching with the human phantom. The optimized antenna had dimensions of \(0.020\lambda _{0}\,\times \,0.015\lambda _{0}\,\times \,0.0013\lambda _{0}\) (where \(\lambda _{0}\) is the wavelength in air of the lowest operating frequency). It covers almost all bands used in wireless body area network (WBAN) applications, including Medical Implant Communication Service (MICS, 402–405 MHz), Wireless Medical Telemetry Service (WMTS, 420–1430 MHz), Medical-BAN (2.36–2.4 GHz) as well as industrial, scientific, and medical (ISM, 2.4–2.485 GHz). The fractional impedance bandwidth was simulated to be 170 % (0.25–3.05 GHz) in free space and 168 % (0.32–3.67 GHz) in the presence of a multilayer tissue model. The fractional impedance bandwidth was measured to be 162 % in free space and 161 % in the presence of a human arm body phantom.

A Novel Delay-Based GFSK Demodulator in 65 nm CMOS for Low Power Biomedical Applications

This article describes how, in recent years, with the development of microelectronics, implantable electronic devices have been playing a significant role in modem medicine. Examples of such electronic implant devices are, for instance, retinal prosthesis and brain implants. It brings great challenges in low power radio frequency (RF) and analog designs. This article presents a low power Gaussian frequency shift keying (GFSK) demodulator designed for Medical Implant Communications Service (MICS) band Receiver. This demodulator utilizes a novel structure that a wide IF range can be handled and presents the smallest Δf/f ratio in any published GFSK demodulators. In theory the demodulation method can be applied to any RF frequency. The demodulator draws 550uA from a 1 V power supply. A maximum data rate of 400 Kbits/s can be achieved within the 300 KHz channel bandwidth defined by MICS. A simulated signal-to-noise ratio (SNR) of 15.2dB at AWGN channel is obtained to achieve 10-3 bit error rate (BER). This demodulator is fabricated on 65-nm CMOS and occupies 0.12mm2 silicon area.

Compact Meander Line Telemetry Antenna for Implantable Pacemaker Applications

&lt;p class="Normal1"&gt;The demand for health technology is increasing rapidly especially in telemetry applications. These applications generally use implanted antennas to be utilized for data transfer from patients to another reader device. This procedure can make the health care more efficient, since it provides fast diagnosis and treatment to the patient. This work presents a design of telemetry antenna to be used in Pacemaker application in Medical Implant Communication Services (MICS) (401 MHz-406 MHz). By introducing Compact Meander Line Telemetry Antenna (CMLTA), length (Ls) and width (Ws) of substrate have been reduced by 36.84% and 40% respectively. The proposed antenna offers advantages of easy fabrications, low cost and light weight with a 133 MHz bandwidth.&lt;/p&gt;

Ultrawideband Technology for Medical In-Body Sensor Networks: An Overview of the Human Body as a Propagation Medium, Phantoms, and Approaches for Propagation Analysis

An in-body sensor network is that in which at least one of the sensors is located inside the human body. Such wireless in-body sensors are used mainly in medical applications, collecting and monitoring important parameters for health and disease treatment. IEEE Standard 802.15.6-2012 for wireless body area networks (WBANs) considers in-body communications in the Medical Implant Communications Service (MICS) band. Nevertheless, high-data-rate communications are not feasible at the MICS band because of its narrow occupied bandwidth. In this framework, ultrawideband (UWB) systems have emerged as a potential solution for in-body highdata-rate communications because of their miniaturization capabilities and low power consumption.

System‐level energy model for data transmission in wireless biomedical implantable systems

This paper develops simple system-level energy models for different kinds of transmitter implementations. Different communication protocols such as ASK, OOK, FSK, PSK are considered to evaluate the energy cost of both the architecture of the system as well as the electronic circuitry. These models are developed for the systems operating in the Medical Implant Communications Service frequency band. These models are useful for the optimisation of system and circuit parameters and provided some guidelines to choose the right modulation and circuit implementation for energy limited wireless transmitters.

Modeling and Optimization of Inductively Coupled Wireless Bio-Pressure Sensor System Using the Design of Experiments Method

This paper presents an approach for modeling and design of inductively coupled wireless bio-pressure sensor system for chronic intracardiac pressure monitoring. Making use of recent advances in microelectromechanical systems and semiconductor technology, bio-pressure sensor is developed as a series LC resonant circuit with a featured pressure-dependent capacitance working at the medical implant communication service band of 402–405 MHz for wireless sensing without power consumption. The microfabricated sensor consists of a planar spiral gold (Au) coil, a series capacitor, an SU-8-based frame structure, and an encapsulated bio-compatible PDMS membrane. Bio-pressure sensor is designed with a small footprint of 3.2 mm $\times $ 3.2 mm for reducing the bleeding and infection risks in surgery. With a limited footprint and desired working frequency, there are many mutually dependent geometry parameters with numerous combined groups of values involved in the full optimization of the system. In order to maximize the performance of system under the design requirements, RF characteristics that affect inductive sensitivity and pressure sensitivity are theoretically analyzed first, and then design of experiments method is applied to model and optimize 3-D electromagnetic models of sensor and sensor system on the derived RF characteristics. The large number of combined groups of values in factorial simulations is thus reduced to a few performance-related design factors. By monitoring the induced peak impedance of the readout coil, the pressure-dependent resonant frequency of the sensor can be detected and measured. The experimental results show that the optimized wireless sensor system has a relatively high average pressure sensitivity of 5.3 KHz/mm Hg at a telemetry distance of 10 mm demonstrating its potential for intracardiac pressure monitoring.

An Implantable Wireless Neural Interface System for Simultaneous Recording and Stimulation of Peripheral Nerve with a Single Cuff Electrode.

Recently, implantable devices have become widely used in neural prostheses because they eliminate endemic drawbacks of conventional percutaneous neural interface systems. However, there are still several issues to be considered: low-efficiency wireless power transmission; wireless data communication over restricted operating distance with high power consumption; and limited functionality, working either as a neural signal recorder or as a stimulator. To overcome these issues, we suggest a novel implantable wireless neural interface system for simultaneous neural signal recording and stimulation using a single cuff electrode. By using widely available commercial off-the-shelf (COTS) components, an easily reconfigurable implantable wireless neural interface system was implemented into one compact module. The implantable device includes a wireless power consortium (WPC)-compliant power transmission circuit, a medical implant communication service (MICS)-band-based radio link and a cuff-electrode path controller for simultaneous neural signal recording and stimulation. During in vivo experiments with rabbit models, the implantable device successfully recorded and stimulated the tibial and peroneal nerves while communicating with the external device. The proposed system can be modified for various implantable medical devices, especially such as closed-loop control based implantable neural prostheses requiring neural signal recording and stimulation at the same time.

Monitoring, Tracking, and Recording Pancreas-Related Health Issues in Real Time

The monitoring of pancreas-related health issues in real-time and outside the medical room is a challenge in the wide e-health domain. This paper introduces WHEAMO, a novel e-health platform which employs medical implants (biosensors), which function as antennas, planted in the pancreas. WHEAMO uses wireless in-body propagation to track, monitor, and record critical parameters, such as glucose. The signal reaches the skin and then it is propagated in an indoor environment (e.g., medical room) over to a terminal equipped with adaptive, user-configurable, and intelligent mechanisms which provide personalized recommendations to varying WHEAMO users (e.g., medical personnel, health care workers, patients). The personalized nature of the provided recommendations is based on patients unique characteristics via a sophisticated knowledge-base. The fundamentals of in-body and on-body wireless propagation and channel characterization have been studied in a series of published works. Researchers have tested both electric-field (dipole) and magnetic-field (patch, loop) antennas. Another important aspect concerns the frequency band in which the signal propagation will occur. Among the frequencies that have gathered scientific and academic interest are the Medical Implant Communication Service (MICS) band at 402-405 MHz, the 900 MHz channel and the industrial, scientific and medical (ISM) radio band at 2.45 GHz.

A Multiband Antenna Associating Wireless Monitoring and Nonleaky Wireless Power Transfer System for Biomedical Implants

This paper presents a multiband conformal antenna for implantable as well as ingestible devices. The proposed antenna has the following three bands: medical implanted communication service (MICS: 402–405 MHz), the midfield band (1.45–1.6 GHz), and the industrial, scientific, and medical band (ISM: 2.4–2.45 GHz) for telemetry or wireless monitoring, wireless power transfer (WPT), and power conservation, respectively. A T-shaped ground slot is used to tune the antenna, and this antenna is wrapped inside a printed 3-D capsule prototype to demonstrate its applicability in different biomedical devices. Initially, the performance of the proposed antenna was measured in an American Society for Testing and Materials phantom containing a porcine heart in the MICS band for an implantable case. Furthermore, to stretch the scope of the suggested antenna to ingestible devices, the antenna performance was simulated and measured using a minced pork muscle in the ISM band. A modified version of the midfield power transfer method was incorporated to replicate the idea of WPT within the implantable 3-D printed capsule. Moreover, a near-field plate (NFP) was employed to control the leakage of power from the WPT transmitter. From the simulation and measurements, we found that use of a ground slot in the implantable antenna can improve antenna performance and can also reduce the specific absorption rate. Furthermore, by including the NFP with the midfield WPT transmitter system, unidirectional wireless power can be obtained and WPT efficiency can be increased.

Dual‐band electrically coupled loop antenna for implant applications

Recent low power implant to off-body communication systems uses both medical implant communication services (MICS) and industrial, scientific, and medical (ISM) frequency bands. In these systems, MICS band and ISM band (2.45 GHz) are dedicated for data transmission and wake-up signal, respectively. This dual band operation which incredibly extends the life time of battery forces designers to use dual band antennas in both implant and off-body sides. In this study, a dual band implant electrically coupled loop antenna is proposed. This antenna as dual of planar inverted-F antenna is a magnetic antenna with inherently low near zone electric field and therefore produces low specific absorption rate (SAR) inside the body. The antenna is miniaturised using a lumped capacitor. In spite of small size of 5 × 5 × 3 mm3, the simulated 1 g average SAR is smaller than reported dual band implant antennas in both frequency bands and makes the proposed antenna a good candidate for implant applications.

Fraction phase based low energy frequency calibration: analysis and design

The study presents the algorithm design, non-ideal effect analysis, architectural analysis and design, circuit analysis and design of an iterative frequency calibration system that corrects frequencies consuming very low energy. The method is based on measuring the `fraction' portion when an oscillator frequency (typically of a radio frequency oscillator) is divided by a fixed reference frequency. It then compares the obtained fraction value with the target fraction value (target frequency divided by the same reference) and finally corrects the oscillator frequency so as to converge it to the target. A salient feature of the proposed architecture of the system is the absence of elements in the radio frequency path which is considered to be the main source of power consumption. The system can be used in applications that do not require stringent phase-locking e.g. wireless sensor nodes. Test of the calibration system has been performed in conjunction with a Medical Implant Communication Service (MICS) band (402-405 MHz) oscillator. Successful convergence has been achieved over a wide range of sampler delay variation and oscillator jitter, which are the circuit level non-idealities that arise in the system.

Fundamental Limits of TOA/DOA and Inertial Measurement Unit-Based Wireless Capsule Endoscopy Hybrid Localization

In this paper, performance analysis of hybrid localization based on radio-frequency (RF) and inertial measurement unit (IMU) measurements for a single wireless capsule endoscopy (WCE) traveling the gastrointestinal tract is studied. Specifically, the multiple body-mounted sensors are considered which are located on the front and back of a patient’s medical jacket and form the uniform rectangular arrays (URAs). With the aim of locating the WCE, two types of RF measurements, namely time-of-arrival (TOA) and direction-of-arrival (DOA), are estimated from the received signals at the URAs transmitted by the WCE, which are integrated with the IMU acceleration measurements via the standard extended Kalman filter. Here, a posterior Cramer–Rao Bound (PCRB) of the proposed TOA/DOA and IMU-based hybrid localization is derived as fundamental limits on squared position error, where the accuracies of TOA and DOA measurements are entailed by means of CRB to account for their dependency on the environmental parameters, while the accuracies of the IMU measurements are addressed with the acceleration measurement error standard deviation. Numerical results are provided, sustained by simulations which verify the millimeter accuracy of the TOA/DOA and IMU-based hybrid localization within the regulation of medical implant communication services and the exactness of the PCRB.

Miniaturized implantable antenna integrated with split resonate rings for wireless power transfer and data telemetry

ABSTRACTIn this article, a new miniaturized implantable antenna (MIA) is proposed for biomedical applications. The antenna is composed of a loop integrated with split resonate rings (SRRs), which produces two resonant modes to make the antenna operate at both Medical Implantable Communications Service (MICS) 402–405 MHz and Industrial, Scientific, and Medical (ISM) 2.40–2.48 GHz bands. Compared to the traditional dual‐band implantable antennas, the proposed MIA has a few advantages: it is small, easy to operate, and has a wide bandwidth. Most importantly, −8 dB coupling strength can be obtained when the distance between the proposed antenna and the external antenna is 5 mm. The vitro test in a minced‐pork environment was performed to demonstrate the reliability of the proposed antenna in the real implantation. The size of the proposed antenna is 152.4 mm3 (10 mm × 12 mm × 1.27 mm). The simulated and measured impedance bandwidths are 43.4% and 33.9% at the MICS band, 64.2% and 58.7% at the ISM band, respectively. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:710–714, 2017

A Low Power Low Phase Noise Oscillator for MICS Transceivers.

A low-power, low-phase-noise quadrature oscillator for Medical Implantable Communications Service (MICS) transceivers is presented. The proposed quadrature oscillator generates 349~689 MHz I/Q (In-phase and Quadrature) signals covering the MICS band. The oscillator is based on a differential pair with positive feedback. Each delay cell consists of a few transistors enabling lower voltage operation. Since the oscillator is very sensitive to disturbances in the supply voltage and ground, a self-bias circuit for isolating the voltage disturbance is proposed to achieve bias voltages which can track the disturbances from the supply and ground. The oscillation frequency, which is controlled by the bias voltages, is less sensitive to the supply and ground noise, and a low phase noise is achieved. The chip is fabricated in the UMC (United Microelectronics Corporation) 0.18 μm CMOS (Complementary Metal Oxide Semiconductor) process; the core just occupies a 28.5 × 22 μm2 area. The measured phase noise is −108.45 dBc/Hz at a 1 MHz offset with a center frequency of 540 MHz. The gain of the oscillator is 0.309 MHz/mV with a control voltage from 0 V to 1.1 V. The circuit can work with a supply voltage as low as 1.2 V and the power consumption is only 0.46 mW at a 1.8 V supply voltage.

Throughput evaluation on multilevel modulation with local frequency offset spatial diversity for 400 MHz band implant communications

One of promising applications for implant communications is a wireless capsule endoscope, which can realise a high quality of medical and healthcare services. However, the regulation of medical implant communication service (MICS) band often employed by the wireless capsule endoscope prevents reliable and high-speed transmission due to its narrowband limitation. In this study, the authors introduce several multilevel modulation schemes with local frequency offset diversity reception into the implant communications to improve the communication reliability and the data rate without any frequency bandwidth extension. Then, the authors evaluate the throughput performances for the proposed multilevel modulation with spatial diversity reception based on propagation characteristics of implant wireless signals derived by a finite difference time domain analysis. Consequently, the computer simulation results demonstrate that the proposed implant communication system can accomplish maximum communication distance of 20 cm ensuring excellently high throughput of 1.5 Mbps under the MICS bandwidth limitation of 300 kHz in a realistic implant communication scenario.