Combining broadband mobile electronics with ultralow-power consumption and miniaturization in implantable semiconductor radio transceiver chips and sensors, healthcare and wellness is rapidly changing across the world. Consequently, new services and applications are emerging that will enable real-time medical sensing and treatment from a distance. Thus, taking ubiquitous medical care to a new level.

Last year, in a keynote speech at the International Microwave Symposium in Honolulu, Prof. Ryuji Kohno of Yokohama National University and director of the University's Medical Information Communications Technology Institute signaled a new direction for advanced wireless communications and introduced medical info-communication technology (ICT) projects and activities in Japan. According to Kohno, under a five-year plan (FY2006-FY2010), called “u-Japan Plan, the Japanese government is aiming to establish a ubiquitous ad-hoc network for medical services that is safe and reliable.

To implement such a medical healthcare service, advanced ICT will exploit technologies like RFIDs, network robots, sensor networks, and mobile communication systems based on advances in ultrawideband (UWB), software-defined radio (SDR), and multiple-input, multiple-output (MIMO) technologies. Consequently, he added, further R&D is needed in areas such as ultralow-power amplifiers and LNAs, software-reconfigurable RF, antennas on implanted chips and cognitive sensor robots. In addition, packaging technology is critical to wearable and implanted devices.

Furthermore, Kohno said that improvements in implanted devices for humans, in combination with implantable radio chips is facilitating in-body communications for supporting new monitoring, diagnostic and therapeutic applications. Toward that end, Kohno described a wireless capsule endoscope developed by Olympus that enables monitoring of the small intestine in a non-invasive manner.

Speaking of implantable semiconductor chips and in-body communications, Zarlink Semiconductor continues to improve its implantable ultralow-power transceiver ZL70101 (See, “Implantable ultralow-power radio chip facilitates in-body communications,” RF Design, June 2007, p. 20.) for medical telemetry systems linking implanted medical devices and monitoring equipment. In fact, according to Zarlink, Given Imaging has implemented this device in a pill camera for diagnostics. Using CMOS imaging, this camera takes pictures and transmits to a recorder at four frames/s with a data rate of 2.7 Mbps. It consumes about 5.2 mW when transmitting and is designed to operate for more than eight hours. FDA approved, some 600,000 patients have swallowed this pill, said Peter Putnam, director of marketing for Zarlink's medical communications group.

Plus, it has been combined with a pacemaker that is in production, noted Putnam. However, the company would not identify the OEM producer in this case. Other such devices targeted include neurostimulators, drug pumps, implantable cardioverter defibrillators (ICDs) and other physiological monitors.

Meanwhile, based on the ZL70101 implantable transceiver, Zarlink has readied a development kit that enables faster design and evaluation of wireless telemetry systems linking implanted medical devices with monitoring and programming equipment.

The ZLE70101 application development kit (ADK) demonstrates the high data rate, ultralow-power and reliable communication link supported by the transceiver. This highly integrated RF chip delivers data rates up to 800 kbps and operates in the medical implant communication service (MICS) 402-405 MHz band. The chip currently consumes 5 mA of supply current in full operation, while incorporating a unique “wake-up” receiver that allows the device to operate in an extremely low current 250 nA in sleep mode.

A commonly used microcontroller is used for the implant and base station platforms to enable rapid integration into a customer's specific system design. The graphical user interface (GUI), running on Windows, interfaces to the MICS RF boards via a USB2.0 interface. The kit also includes an applications development platform (ADP100) board that interfaces with the PC through a USB2.0 interface to the implant or base station mezzanine boards. The application implant mezzanine (AIM100) board performs all MICS-related implant communications. This board includes the ZL70101 transceiver, discrete circuits including matching networks for normal data transmission and wake-up operation, an application microcontroller connected to the ZL70101 over an industry-standard SPI bus, and an SMA connector interface to a PCB-based loop antenna (Figure 1).

Additionally, the base station mezzanine (BSM100) board performs all MICS-related base station/monitoring equipment communications processing. The board includes the same features as the AIM100, with the addition of a wake-up transmitter subsystem and a received-signal-strength indicator (RSSI) filter for performing clear-channel assessment (CCA). The BSM100 also includes a dual-band antenna optimized for performance in the MICS band and supporting wake-up signaling. To minimize development time, the ADP100, AIM100 and BSM100 are fully supported by embedded firmware with thoroughly commented source code to help developers quickly understand the programming requirements of the chip while allowing for firmware reuse.

Concurrently, Zarlink is working with the European consortium Healthy Aims based in the UK. Researchers are developing medical technologies, including implantable devices that integrate wireless capabilities. One application is functional electrical stimulation (FES) that uses signals from implants to stimulate muscles to allow limb movement. Zarlink is also developing in-body antenna for this application.

Combining the skills of its healthcare and wireless divisions, Cambridge Consultants has developed a control and communications architecture for in-body medical diagnostics and therapeutic applications, called SubQore. Designed to be compatible with the MICS band, it offers a range of 2 m when implanted under the skin, according to Cambridge Consultants manager for surgical and interventional products Mark Manasas. He added, “It is a customizable architecture which a client could turn into a custom ASIC. I'm not sure about the simulation status, but the design incorporates a range of pre-developed low-power silicon blocks that have been proven in previous designs.”

Meanwhile, Zarlink continues to drive down the power consumption of the implantable transceiver chip. Toward that goal, it is readying 70102 that will exploit 0.18 µm RF CMOS process with new radio architecture and modulation techniques. It is expected to be unwrapped in the second half of this year.

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