Bluetooth chip manufacturer CSR recently announced the sale of its one billionth chip, making the technology arguably the most widely used wireless transmission system. With chipset prices dipping to as little as $1 each, the appeal of Bluetooth technology for manufacturers seeking cost-effective wireless capability is expected to rise sharply in the foreseeable future.
However, since its inception, the technology has been lacking well-defined standards within the medical industry, resulting in patchy communication between devices of differing manufacturers and constrained market growth. "Up to this point, companies have generally used the Bluetooth Serial Port Profile with proprietary data formats," says Robert Hughes, chair of the Bluetooth SIG Medical Devices Working Group and health standards architect within Intel's Digital Health Group.
"The industry has been longing for standards to improve interoperability and reduce engineering and development costs and this drove us to develop the Health Device Profile (HDP).
"On the data side alone, there are dozens of different ways to represent blood pressure data. One of our priorities was to establish a standard way of representing device data so that, when a blood pressure device sends its data to a recipient device, those systems will be able to recognise and accurately interpret it."
During the development process, the Medical Devices Working Group coordinated with the IEEE 11073 Personal Health Devices Working Group to develop a common data standard that can be used by Bluetooth, USB and other transports.
"Companies that invest in the development of these IEEE-11073 data standards for their Bluetooth HDP products, will be able to reuse components implementing the 11073-20601 protocol for products based on the USB Personal Healthcare Class," says Hughes.
"The IEEE-11073 organisation defined the data exchange protocol and what the data looks like for each device type and the Medical Devices Working Group defined the connection and transport standards specific to Bluetooth. So, whether you get blood pressure from a USB health device or a Bluetooth HDP device, the data will be understood once it reaches your PC, phone or other device and ultimately the caregiver. There was a clear lack of standards in this part of the industry. These teams have laid an excellent foundation for new uses and enabled market growth."
Whenever Bluetooth technology is discussed, the topic of security usually follows. But though it is frequently assumed that Bluetooth data transmission is not very secure, Hughes says that this is a common misconception. "Bluetooth has many tools in its toolbox related to security and in the past developers had not taken full advantage of these.
"In addition, developers that do not follow good practices may inadvertently expose security holes. This has led to the misconception that Bluetooth is not secure," he explains. "Bluetooth 2.1 introduced secure simple pairing (SSP) which did a lot to make good security easier. The use of SSP is required for all 2.1 devices and mandates encrypted connections between devices.
"SSP uses a more advanced pairing mechanism based on public key cryptography which eliminates many of the security problems that pre-2.1 solutions had." Bluetooth devices must be paired in order to communicate, forming what is called a piconet.
"In the Bluetooth Health Device Profile, encryption and authentication of all connections is required even when using Bluetooth versions earlier than 2.1," says Hughes. "Though there are examples where encryption may be viewed as unnecessary, such as encrypting body temperature, there are many more examples where unencrypted data may expose a privacy risk. For example, a person using a blood glucose measurement device may not want others to know they are diabetic. To err on the side of privacy and security, we made the decision early on to encrypt all data regardless of the type."
Another common misconception about Bluetooth is that it is susceptible to interference problems. In actuality, Bluetooth chipsets since version 1.2 have the ability to detect and avoid environmental interference and have contributed to making the technology more robust. The feature is called adaptive frequency hopping.
Bluetooth devices use fast frequency hopping (up to 1,600 times per second) to mitigate the effects of interference from other devices in the 2.4GHz Industrial Scientific and Medical (ISM) band. When interference in the Bluetooth band is detected, the devices agree to update their hopping sequence to hop around the interference, being a friendly neighbour for other nearby devices while simultaneously increasing performance by avoiding collisions.
It is easy to see why the technology has become so popular and why health device manufacturers are seeking new ways to include it within the clinical and home health setting.
"Most of those participating in our group feel the volume opportunities of this technology lay in the personal healthcare area of the market," says Hughes. "If you have an at-risk condition, it may be valuable to routinely collect and record your health data, allowing you to track your condition and share this with a remote care provider.
"Or a doctor who has discharged a patient from hospital may want to monitor and track their condition remotely to make sure that they are on a good trajectory for recovery. Using a Bluetooth monitoring device will allow you to not only record data easily at specified intervals, but also far more accurately than writing it down and later transcribing it for use by your doctor."
The flexibility of Bluetooth and the HDP also allows for scheduled data transmission intervals, commencing when certain clinically set thresholds are tripped or on a regular basis according to a person's individual health needs. From there, the information can be transferred over POTS, broadband or GSM anywhere in the world to a doctor or anyone else who is responsible for the patient's care.
The last attempt to standardise medical device connectivity was spearheaded by Hewlett Packard and the Medical Information Bus during the 1980s. Unfortunately, these standards met with industry resistance as many manufacturers preferred to retain their proprietary systems.
The IEEE 11073 Personal Health Devices working group was formed in 2006 to focus on personal healthcare applications and has made significant progress to define a more streamlined standard in a short time. This standard is referred to as the ISO/IEEE 11073-20601 data exchange protocol and was influenced by the original 11073 work, but optimised for personal healthcare devices such as blood pressure meters, blood glucose, temperature and weight scales.
Despite the lack of adoption for the original clinical IEEE 11073 standards, industry support for the 11073-20601 and related device specialisations has been impressive. The new standard is set to be adopted as part of the Consolidated Health Informatics initiative and will be used by the Integrating Healthcare Enterprise patient care device committee too.
The adoption of the new Bluetooth health device standard ushers in an opportunity for manufacturers to qualify their products under internationally recognised guidelines. With organisations such as the Continua Health Alliance announcing their adoption of the new standard, the market is set to move swiftly through transition. The organisation represents 150 member companies including payer members of government and the insurance industry who can help drive the market.
"When we start to see these devices transmitting data to doctors and caregivers in large scale, I firmly believe that we will see a positive effect on healthcare including much-needed cost reductions," says Hughes. "I expect this will happen quickly as more and more manufacturers line up to deploy devices."
In terms of transition to the new standard, Hughes believes that manufacturers already using Bluetooth technology need minimal investment to become compliant. "I think HDP and the 20601 standards are necessary elements for growing the market," he says. "In terms of cost, Bluetooth is very attractive. With over 2 billion devices shipped, and volumes on the rise, the cost of integrating Bluetooth has been steadily declining. The volume implications in the health market are significant enough for the world's leading health and technology companies to become heavily involved."
Though high-volume markets will see a mass transition, many smaller markets will remain untouched. "There are valid reasons for some devices to remain proprietary," says Hughes. "This is especially true in more life-critical applications where devices are only meant to interact with specific devices from the same manufacturer. This is a more specialised market and for these applications, companies will not likely want others to connect to their devices because it may expose risk to the patient."
With the HDP scheduled to be approved in the early summer of 2008, the Bluetooth SIG is already working on addressing health and fitness applications using next-generation technology referred to as Bluetooth ultra-low power (ULP). ULP, previously known as Wibree – a digital radio technology developed by Nokia Research Centre – has a transmission range of 10m and can run off button cell batteries.
ULP is ideal for any design with limited power resources and low data rate applications that require wireless capability. The technology was developed to complement existing Bluetooth applications. The Bluetooth SIG acquired the technology through a merger with the Wibree Alliance last summer and has since begun integrating it into new specifications. Future Bluetooth health products will be able to take advantage of ULP.
"ULP is designed to work for applications that are currently not suited for Bluetooth today and in some cases not possible," explains Hughes. "Bluetooth wasn't really designed for devices that run off button or coin cell batteries, such as a fitness watch, pedometer or heart rate monitor," he continues.
"ULP development efforts are very strong in the SIG and a large segment of the target applications lies within the fitness and healthcare industry. Devices such as sports watches will be able to measure your heart rate, temperature, and calorie expenditure and send that collected data via ULP to a phone or laptop to aggregate that data for personal tracking or sharing with a personal trainer.
"The key is that Bluetooth ULP utilises the same radio as Bluetooth so, for almost no additional cost, ULP can be added to existing Bluetooth silicon. That means that newer phone and PC devices with dual-mode Bluetooth silicon can receive information from a ULP sports watch, foot pod or pedometer in addition to other health devices that use regular Bluetooth.
"The number of applications for this low power technology is expected to be significant. ULP is expected to further expand on the ability to collect fitness and health data for the growing market of low cost, mobile applications. There is a lot of interest being generated in ULP and the core specifications and initial profiles are estimated to be released sometime in mid-2009."
BLUETOOTH HIGH SPEED
Currently, the only area where Bluetooth technology may fall short is data transmission speed. But Bluetooth is working on specifications to pair up with high data rate radios like 802.11 and ultra wide band (UWB), officially known as "Seattle". The new Bluetooth wireless specification, currently in development by Bluetooth SIG and Wi-Media Alliance, will increase transmission speeds by many times that of Bluetooth 2.1. Using an 802.11 radio, compliant devices will be able to deliver data at speeds of 54Mbps and even higher using UWB.
"In the Medical Devices working group, some of the high data rate applications being discussed relate to devices such as ECGs and EEGs," says Hughes. "Devices such as these typically use high numbers of wires and channels with data requirements that exceed the capabilities of current Bluetooth technology. Companies within the healthcare industry have expressed a desire to eliminate cables and have true wireless transmission for these data types. Seattle will deliver the speed required for these applications and the HDP will be able to take advantage of this new capability."
Members of Bluetooth SIG envisage a time when wireless sensors will be able to provide early detection of chronic conditions, reduce unnecessary trips to the doctor, and help to improve the health of those who use them by making timely data available to both patient and caregiver. The group is optimistic that these efforts will benefit patients while simultaneously increasing efficiency, lowering data recording errors and reducing costs. Many are hopeful that this will become a reality in the near future.