MHz Medical Implant Communication Service Research Articles

A Millimeter-Scale Crystal-Less MICS Transceiver for Insertable Smart Pills.

This paper presents a millimeter-scale crystal-less wireless transceiver for volume-constrained insertable pills. Operating in the 402-405 MHz medical implant communication service (MICS) band, the phase-tracking receiver-based over-the-air carrier recovery has a ±160 ppm coverage. A fully integrated adaptive antenna impedance matching solution is proposed to calibrate the antenna impedance variation inside the body. A tunable matching network (TMN) with single inductor performs impedance matching for both transmitter (TX) and receiver (RX) and TX/RX mode switching. To dynamically calibrate the antenna impedance variation over different locations and diet conditions, a loop-back power detector using self-mixing is adopted, which expands the power contour up to 4.8 VSWR. The transceiver is implemented in a 40-nm CMOS technology, occupying 2 mm2 die area. The transceiver chip and a miniature antenna are integrated in a 3.5 × 15 mm2 area prototype wireless module. It has a receiver sensitivity of -90 dBm at 200 kbps data rate and delivers up to - 25 dBm EIRP in the wireless measurement with a liquid phantom.

Identification key scheme to enhance network performance in wireless body area network

Wireless Body Area Network (WBAN) refers to a group of small intelligent electronic devices placed on the human body to monitor its vital signals. the efficiency of network performance in health care applications is one of the most important prerequisites for designing an effective surveillance system. However, none of the previous studies have succeeded in proposing an effective scheme that could cover the requirements for effective network performance or the development of the WBAN system capable of sending and receiving vital patient data efficiently. The aim of this paper is to enhance the performance of the network in WBAN. In addition, to verify the transfer of patient data from sensors on the body to receivers with the least value of possible packet loss, a solution is developed that can reduce the value of packet loss, end to end delay and increase the value of throughput, relying on confirmation and matching data between the sender and receiver devices. A new scheme known as the Identification Key Scheme (IKS) is proposed based on the newly available 402–405 MHz Medical Implant Communication Service (MICS). The analysis of the network performance was implemented in real WBAN dataset and used the Multi-Parameter Intelligent Monitoring for Intensive Care (MIMIC) database. MIMIC database included the data recorded from 90 Intensive Care Unit (ICU) patients. In this study, OMNET++ was used as the network simulation tool to design and evaluate the proposed scheme. The results showed that IKS was able to reduce number of packet loss and end to end delay with increased throughput. This is an indicator of the ability of IKS in providing efficient network performance between devices in the WBAN application.

Feasibility Study of Using the Housing Cases of Implantable Devices as Antennas

A novel antenna design for implantable pacemakers is proposed. The housing of a pacemaker is utilized as an antenna to cover both the 402–405 MHz Medical Implant Communication Service band and the 433-MHz Industrial, Scientific and Medical band. This is achieved by exploiting radiating characteristic current modes of the housing case. These modes are excited using a capacitive coupling element with the help of a matching circuit. The radiation pattern of this antenna is optimized to be in a desirable direction away from the body (off-body direction). The ability of the proposed antenna for communications is demonstrated using a transceiver and a base station at 433 MHz. A communication range of 1 m is established when a transmitter with the proposed antenna is implanted in a rabbit and the power fed by the transceiver to the antenna is $25~\mu \text{W}$ . A longer range of up to 19 m can be established with the maximum allowable transmit power within the safety limits. Furthermore, the far field wireless power transfer through the proposed antenna is investigated by experiment. A received power of up to $22.38~\mu \text{W}$ by the proposed antenna is demonstrated when an equivalent isotropically radiated power of 140 mW is transmitted 1 m away from a transmitting antenna. From the same transmitting antenna in the same distance, a power of 4 mW can be received when the transmit power is within safety limits. This power can be used to recharge a small battery or a capacitor, which can potentially cover the communication power consumption of the pacemaker and hence extend the life span of the primary battery.

Performance Evaluation on RSSI-Based Localization for Capsule Endoscopy Systems with 400MHz MICS Band Signals

SUMMARY One of promising application offered by implant body area networks (BANs) is a capsule endoscope localization system. To begin with, this paper performs finite-difference time-domain (FDTD) simulations on implant BAN propagation with a numerical human model, and investigates the propagation characteristics of implant BAN signals at 400 MHz medical implant communication service (MICS) band. Then, the paper presents a capsule endoscope localization system which utilizes only received signal strength indicator (RSSI) and two estimation methods, such as a maximum likelihood (ML) estimation method and a least squares (LS) method. Furthermore, we evaluate the two localization methods by two computer simulation scenarios. Our computer simulation results demonstrate that the ML localization can improve the location estimation accuracy as compared with the LS localization, that is, our performance comparison reveals that a careful consideration the propagation characteristics of implant BANs signals is efficient in terms of estimation performance improvement in capsule endoscope localization.

Bandwidth enhancement and size reduction of an implantable PIFA antenna for biotelemetry devices

AbstractBy means of embedding hook‐shaped slots at the edges of the radiating patches for a stacked planar inverted‐F antenna (PIFA), functions of bandwidth enhancement and size reduction can be achieved for suitable use in implantable biotelemetry devices. The designed antenna with overall size of only 8 × 8 × 1.9 mm3 provides a monopole‐like radiation pattern, a radiation efficiency of 0.55%, and a wide −10 dB impedance bandwidth of 122 MHz covering the 402–405 MHz medical‐implant‐communication‐service (MICS) frequency band. Comparing with the reported most compact antennas, the proposed design obtains not only 144% wider bandwidth but also 36% more compact structure size. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 755–757, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24142

Integrated VCOs for Medical Implant Transceivers

The 402–405 MHz medical implant communication service (MICS) band has recently been allocated by the US Federal Communication Commission (FCC) with the potential to replace the low-frequency inductive coupling techniques in implantable devices. This band was particularly chosen to provide full-integration, low-power, faster data transfer, and longer communication range. This paper investigates the design of a voltage-controlled oscillator (VCO) that will be an essential building block of such wireless implantable devices operating in the MICS service band. Three different integrated quadrature VCOs that meet the requirements of the MICS standard are designed in 0.18 μm TSMC CMOS process to propose an optimum choice. Their performances in terms of power consumption, die area, linearity, and phase noise are compared. The fabricated VCOs are a four-stage differential ring VCO, an LC tank VCO directly loaded with a poly-phase filter, and an 800 MHz LC tank VCO with a high-frequency master-slave divider. All three architectures target a VCO gain of Kvco = 15 MHz/V with 3 calibration control and 2 frequency-shift keying (FSK) control signals and are designed for 1.5 V supply voltage in a 0.18-μm standard CMOS process.

Implantable Broadband Circular Stacked Pifa Antenna for Biotelemetry Communication

A compact circular stacked planar inverted-F antenna implantable for biotelemetry communication in the 402–405 MHz medical-implant-communication-service (MICS) frequency band is presented. By properly embedding a circular hook-shaped slot to each radiating patch of the proposed PIFA structure, antenna size and impedance bandwidth can be significantly improved. The constructed antenna presents a broad 10 dB impedance bandwidth of 84 MHz from measurement by inserting it inside the skin-simulating fluid. Also, the proposed antenna has characteristics of a compact size with a radius of only 5 mm, a radiation efficiency of 1.3%, and a monopole-like radiation pattern suitable for implantable device use.