Nikkei Electronics Asia -- July 2007
Analysis
Medical, Health Care Drive Wireless Innovations

The use of wireless communication in the medical and health care sectors is set to increase rapidly, improving patient care, staff efficiency, and the ease with which equipment can be used.

"The use of wireless communication in the medical and health care sectors will grow for the next 15 years. I've been involved in wireless for a long time, but it looks like the next years are going to be exceptionally interesting," predicted a professor in the wireless communications field at a Japanese university. A source in the Dept of Diagnostic Imaging of the Tochigi Cancer Center of Japan added, "We want to make even more use of wireless... I hope industry forges ahead with new technology development."

In the medical and health care fields, the movement to utilize wireless communication technology is accelerating. In medicine, for example, wireless is now being utilized on a significant scale for communication with equipment implanted inside the human body. In health care, industry is showing interest in tiny sensors worn on the body, which can make it simple to collect data with wireless technology. The collected data can be transmitted to a remote center via broadband link, mobile phone network or other means, and databased for a variety of applications. Health management services for individuals, providing support for prevention of "metabolic syndrome", for example, are also launching, providing yet another boost for the development of new wireless communication technology. 

Firms active in the medical and health care fields hope to leverage wireless communications to develop more sophisticated services, and improve the ease with which equipment can be used. Manufacturers involved in developing new wireless technologies, meanwhile, have high hopes for a new application area for the wireless communication technologies evolved for mobile phones and other uses (Fig 1). Low-power systems operating over short ranges with relatively weak outputs are expected to show exceptional development.

No More Cable Spaghetti
The reason why interest in the application of wireless communication technology in the medical and health care fields is burgeoning is that wireless systems have become much more common, and reliability has improved. The notion that radio waves are taboo when it comes to medical equipment is beginning to seem misguided. 

In medicine, for example, the use of wireless technology as a way to reduce load on patients undergoing treatment is not new. "Patients undergoing treatment are fitted with a variety of sensors to acquire data, and many of them are attached to the measurement instruments with cables," explained deputy director Ryuzou Sekiguchi, Dept of Diagnostic Imaging, Tochigi Cancer Center. "The patient's body is buried in spaghetti. If all those cables can be eliminated, it would be a lot easier for the patient to move, and that would be an enormous improvement. The measurement instrumentation in the hospital is also wired up with countless cables... I always think of how much simpler life might be if they all used wireless." 

Apprehension about using wireless medical equipment, stemming from fears of potential problems associated with using radio waves, has been a major obstacle to achieving this goal, but the situation is changing. Some medical institutions are actively introducing wireless technology to improve the work efficiency of medical personnel, such as nurses. Nurses can carry a PC with wireless local area network (LAN) support right to a patient's bedside; pharmaceutical dosages and other data can be fed into the electronic record in real time, for example. Associate Prof Eisuke Hanada, Dept of Medical Informatics at the Shimane University School of Medicine in Japan, said, "We are actively utilizing wireless networks to improve patient service quality, work efficiency and other points." People in the industry are beginning to recognize that wireless networks like these are effective in acquiring sensor data.

Home Monitoring
The Japanese Ministry of Internal Affairs & Communications is steadily hammering out the legal framework for the use of radio frequencies in medicine. In the spring of 2007, for example, radio facility regulations were revised for 400MHz waveband systems used in implants. Specifically, the new regulations made it possible to connect implants such as pacemakers or implantable cardioverter defibrillators (ICD) to external equipment using radio. 

The goal eventually is to use home monitoring systems (Fig 2) to monitor pacemakers, ICDs and other implanted electronics. Usually these implants are checked every three or four months, allowing technicians to check the remaining charge on primary batteries, the sheathing on the leads passing electricity to the heart (epoxy resin, etc) and other points. If there were a defect in the insulating sheath, it could cause the patient agony.

Until recently, inspections like these have been performed in Japan only in hospitals and other places that have the necessary equipment. Overseas, however, simple instrumentation is being used in the home that can receive the weak radio signals from implanted equipment like pacemakers and ICDs over a range of several m. Biotronik of Germany and other firms, for example, already offer such home monitoring systems. The legal framework being drawn up by the Ministry of Internal Affairs & Communications is considering ways of making it possible to use the same type of home monitoring systems in Japan. 

Implants have also been developed which are capable of exchanging information with mobile phones. The status of the implanted equipment (lead impedance, etc) is transmitted to a medical institution periodically, about once a day, for monitoring. In the future, it is hoped that remote monitoring over the mobile phone network could replace periodic inspections. Patients who now have to spend several hours visiting a medical institution for such inspections could have their lives greatly simplified as a result.

Capsule Endoscopes
Capsule endoscopes can be swallowed to allow photography of the inside of the digestive tract, for example; and here as well wireless transceivers are expected to become invaluable. 

Capsule endoscopes measure about 9 to 11mm in diameter, and about 23 to 26mm in length, but contain cameras with resolutions of about 400,000 pixels. Imagery is transmitted outside the body using radio operating in the 1.8GHz band. 

People are already experimenting with wireless control of these capsule endoscopes from outside the body, too. The capsules are not equipped with propulsion mechanisms, such as propellers, so it is impossible to make them stop at a specific site. Detailed diagnosis of the digestive tract, however, would be much more effective if the capsule could be stopped and multiple photographs taken. According to Jiro Maruyama, president and chief executive officer (CEO) of RF Co Ltd of Japan, "We eventually want to be able to halt the capsule endoscope at specific sites. We're working on a way of having the capsule discharge a bonding agent on command from a remote controller." Implementation of this function would require transceiver functionality.

Standardizing BAN
Two key technologies supporting emerging services in the medical, health care and other fields are wearable sensors and short-haul wireless communication technology used to connect them to gateway equipment. Body area networks (BAN) are attracting considerable attention recently as such a technology specifically for these applications (Fig 3).

Work has already begun on an international BAN standard that is expected to help reduce transceiver cost and promote widespread adoption. The requirement specifications reveal an outline of the short-range wireless system expected to be adopted in the medical and health care fields. Range is from several dozen cm to about two m, and the data transfer rate is a maximum of about several hundred kbps. Low power consumption is assigned a higher priority than specs like data transfer rate or range, however. The sensors are worn on (or in) the body for long periods of time, making long-term battery drive a key consideration. Other points to keep in mind are the need to avoid wavebands readily absorbed by the body, making sure that interference with other medical electronics is minimized, etc.

Implants, Wearables
Broadly speaking, there are two types of BAN: wearables, where equipment is worn on the body or kept close to it; and implants, where equipment is actually placed inside the body. 

A variety of standards cover radio communication with wearables (Table 1). The 2.4GHz band approach, for example, includes solutions like Bluetooth, widely used in applications such as mobile phones and headsets; WiBree, a simplified version of Bluetooth consuming only one-tenth the power; and ZigBee, which is gradually evolving and penetrating equipment networks. 

Of these, WiBree, which began to show significant standardization activity in the second half of 2006, is designed primarily for use in wearable health care applications. Intended for use in things like wristwatches and pedometers, power consumption is planned to be only a few mW in operation, and several uW in standby. A large number of companies with strength in low-dissipation technologies, such as Seiko Epson Corp of Japan, have announced semiconductor development projects. Nordic Semiconductor ASA of Norway, which developed the low-power wireless technology used in the Nike+iPod Sport Kit jointly developed by Apple Inc of the US and Nike, Inc of the US, is actively developing wireless integrated circuits (IC) for WiBree.

Prototype Systems
Implanted electronics, on the other hand, seem likely to end up using ultra-wideband (UWB) technology. UWB utilizes a wide bandwidth so that the transmission power per unit of bandwidth is low, keeping radiated electromagnetic interference (EMI) very low (-41.3dBm/MHz), which not only minimizes the possibility of causing the medical equipment to malfunction, but may also reduce transceiver circuit power consumption. 

A UWB standard already exists for communication by this type of sensor: IEEE802.15.4a, drawn up by the IEEE802 Committee. With an xmit power of -41.3dBm/MHz or less, the data transfer rate is 850kbps or higher. At that rate it would be possible to handle even electrocardiograms over wireless, even though they demand a relatively high bitrate.

With IEEE802.15.4a, it is possible that transceiver power consumption could be no more than a few mW. The National Institute of Information & Communications Technology (NICT) of Japan, for example, is engaged in research and development into wireless transceiver systems for BANs, and currently envisages using IEEE802.15.4a. The organization displayed a similar prototype system (Fig 4) at Wireless Technology Park 2007, held early April in Yokohama, Japan. 

The NICT has not been licensed to operate an experimental station using UWB signals, and so the network is currently cabled, using slightly different output signal levels, bandwidth, etc. For example, the ALOHA system is not used for MAC access control or modulation, and the USB pulse repetition frequency is different. The max data rate is defined as 850kbps in IEEE802.15.4a, but the prototype system has a ceiling of 66kbps.

There are problems with using IEEE802.15.4a, however, because of the 850kbps data rate. Japanese law requires that UWB speed be no less than 50Mbps, which means before the IEEE solution can be used in Japan, the Japanese legal framework covering UWB will have to be overhauled.

by Hiroki Yomogita

Websites:
Apple: www.apple.com
Biotronik: www.biotronik.com
Nike: www.nike.com
Nordic Semiconductor: www.nordicsemi.no
Seiko Epson: www.epson.co.jp/e

MOST POPULAR ARTICLES

24 Hours | 7 Days