Low power extends battery and human life

Improved energy efficiency may make life easier for smartphone users but it will also transform patient care, says Ian Ferguson

Lower power consumption and longer battery life are not just issues for smartphone users. They will also have a huge impact on medical care, says Ian Ferguson.

The latest, ultra-high performance smartphones have batteries that last more than a day and use sophisticated techniques for minimising power drain. That issue of energy-efficient design is in the forefront of system designers' minds — and not just for smartphones.

An increasingly pertinent application for low-power electronics lies in the medical industry, where technology plays a key role in improving and even saving lives.

Around the world, healthcare organisations with often diminishing budgets need to deal with many challenges, from an ageing population to childhood obesity. Advances in energy efficiency, processing performance and logical integration of processor functionality will deliver efficiencies for the industry through digitalisation, miniaturisation and personalisation.

Reducing system costs
With a public service such as the NHS in the UK, a fundamental enabler for all three of these is driving down system cost. So silicon suppliers need to be able to produce chips that have an attractive price to ensure widespread adoption.

An important way to achieve savings is through the integration of functionality at the chip level, which enables device manufacturers to pack more capabilities into smaller, cheaper devices.

Miniaturisation refers to tests and treatments that were once available only at a few central hospitals, due to the large size and high cost of equipment, now being implemented using much smaller, cheaper kit at regional hospitals.

Many of ARM's silicon partners are driving the low-power innovations that enable these advances in the medical industry. For example, Texas Instruments chips already power many medical devices used in hospitals, including blood-pressure monitors, blood-glucose monitors, digital X-ray machines and portable ultrasounds.

Personalisation encompasses the set of devices that reside with you and communicate data securely over a public network. These ever-more-sophisticated electronic devices are starting to migrate into patients' homes too.

Increase in home monitoring
A growing trend in the medical industry is home monitoring, whereby out-patients can be given medical equipment that connects directly to a hospital or a GP surgery. Patients can connect from home, so they can still be monitored for any health-related irregularities, with real-time feedback.

Of course, these advances are all being made possible by the spread of consumer broadband, with over 73 percent of households in the UK now having an internet connection. These home-monitoring technologies could play a pivotal role in cutting costs while making sure the correct treatment is accessible to people with a debilitating illness.

To illustrate, according to Alzheimer's Disease International, treatment related to dementia will cost the world up to £388bn this year. This cost could be reduced using...

... lower-cost electronics components in monitoring equipment, enabling friends, family and doctors to check on a patient's whereabouts and health.

Just as consumers want their mobile phone charge to last all day, the medical industry is realising the importance of a longer battery life in helping medical professionals offer better care.

Patient details are now often digitised, transferred and stored on smartphones and other mobile devices and carried by doctors and nurses. Apple iPad devices are also increasingly being used by medical professionals for patient evaluation and information access.

Developments in medical technology
Looking ahead, we'll see some intriguing advances for equipment that combines information from multiple sensors with GPS location and wireless connectivity, especially if battery life can be extended. A battery in a pacemaker today needs replacing every five to 10 years, which means surgery.

Some believe we'll soon use a smartphone to monitor body vitals, but I don't think it will be the dominant device.

Research by the University of Michigan (PDF) offers useful insight into prolonging battery life. Instead of running a 32-bit processor at high frequency, the processor is run at just 73kHz. A 32-bit processor is able to process readings more quickly than an 8-bit controller, saving energy. This digital logic, combined with a solar cell and a thin-film solid-state Lithium battery, is expected to run for five years without recharging.

Wireless sensing of intraocular pressure could be used to detect and track the progression of glaucoma. For a system inside the body, vibrational energy could be used to power the battery.

For devices to be placed inside the body, the maximum size for the component is often 1mm³. Due to these constraints, stacked die could offer significant benefits, especially as the ideal process geometry for the accelerometer, battery, wireless and digital logic are likely to be different.

Smartphones will not dominate
Some believe we'll soon use a smartphone to monitor body vitals, but I don't think it will be the dominant device for several reasons. First, older generations in particular may consider a smartphone simply too intimidating.

Simplicity will rule: push-to-talk functionality with a few buttons to control the system, with an accelerometer to detect a patient falling over, other sensors to provide heart rate and other body statistics, and a GPS component to deliver location information.

Secondly, these systems need to be bound to the patient, so they must be waterproof and continue to operate even if they are knocked around. Thirdly, cost is a key issue as one business model will be for these systems to be given away for free.

The development of lower power, higher performance processor technologies means the evolution of medical devices becomes a literally life-changing one.

Next-generation processor technology advances that enable the widespread adoption of more energy efficient, secure and constantly connected medical devices will help medical professionals work more effectively and offer enhanced care to patients.

Ian Ferguson is director of embedded and enterprise solutions at microprocessor design company ARM.