Advances in the design of wearable technology is helping to sever the ties between patients and diagnostic equipment, explains Steve Evanczuk, Mouser Electronics.
For healthcare providers, accurate diagnosis and treatment depends on a clear and continuous picture of an individual’s health, something that can’t be achieved with infrequent tests carried out in doctor’s surgeries. These at best offer just a static snapshot of an individual’s ever-changing health dynamics. For the patient, regular surgery visits or dealing with medical equipment installed in the home becomes disruptive and too often translates into noncompliance with health treatment plans.
The ability to review health data remotely through wearables promises measurable improvements in healthcare. According to the international Groupe Speciale Mobile Association (GSMA), a study of patients in the USA with chronic heart failure found that remotely monitored patients had fewer and shorter hospital stays than a control group, while a separate study noted that remote monitoring of patients with chronic heart failure could reduce re-hospitalisations by as much as 72%. Like the GSMA, the Continua Health Alliance, a not for profit industry organisation of healthcare and technology companies, sees remote monitoring, or telehealth, as a key enabler for healthcare solutions needed to address skyrocketing spending on chronic disease already surpassing $500 billion/yr.
Wearable electronics can directly address these concerns, providing individuals and their healthcare providers with a clearer picture of health trends than available in the past. Rather than occasional snapshots of vital statistics taken in doctors’ surgeries or hospitals, wearable health and wellness products offer a long-term view of an individual’s physical condition. In fact, more advanced wearables will even provide instant response to health events or allow physicians to perform remote diagnostics and limited treatment.
While fitness monitors have for years helped individuals track their heart rates around the clock, a new wave of more sophisticated wearables is looking to offer continuous updates of important diagnostic data. For example, iHealth Lab’s ambulatory blood pressure monitor, wireless ambulatory ECG and wearable pulse oximeter all combine wearable sensor systems that transmit data to smartphones using Bluetooth. The blood pressure monitor is designed to be worn inside a vest to provide 24-hour monitoring without changing a user’s normal daily routine. The ECG device’s electrodes and monitor are combined in a lightweight unit that attaches directly to the user’s chest and can be worn under clothing, pushing data to the cloud for access by healthcare providers. Similarly, the pulse oximeter uses a fingertip sensor attached to a comfortable wristband, enabling oxygen saturation (SpO2) measurements 24 hours/day.
For their part, fitness trackers are shrinking in size, allowing users to wear them continuously, comfortably and inconspicuously. Next-generation fitness wearables such as the Garmin Vivofit, LG Lifeband Touch and Sony Core are becoming more powerful, providing more data to more sophisticated apps able to offer better guidance on health and fitness.
Behind the rapid emergence of this new generation of wearables for wellness lie dramatic advances across a broad spectrum of technologies including sensors, ultra low power processors, wireless communications, flexible electronics and packaging. In fact, one of the key breakthroughs in the past few years has been the ability of manufacturers to weave sensor arrays into clothing, enabling development of diagnostic instruments that can be worn comfortably and unobtrusively.
For example, AiQ Smart Clothing embeds tiny stainless steel threads into fabric, providing a conductive mesh for embedded sensors able to monitor skin temperature and moisture as well as bioelectric measurements. Embedded unobtrusively in clinical garments, this sensor array non-invasively and continuously provides an ongoing source of vital statistics.
Looking to reduce misdiagnosis in current screening procedures, First Warning Systems is using its own embedded sensor technology in its smart bra, designed to deliver non-radiogenic, non-invasive diagnostic data while being worn like any other bra. The company’s smart bra embeds multiple sensors to collect data for predictive analysis by software that can actually alert physicians to possible abnormalities. Confirmed in clinical trials, First Warning Systems’ technology monitors tissue changes that occur before tumours appear, offering an affordable early warning that helps make current screening practices more effective.
As well as monitoring, wearables are also gaining traction in treatment. Thimble Bioelectronics is developing a small patch designed to offer mobile treatment for localised pain using transcutaneous electrical nerve stimulation (TENS) and electromyostimulation (EMS). TENS/EMS devices have so far tethered individuals to equipment installed at homr or in treatment rooms. By providing the ability to gain long term, immediate treatment, a mobile patch offers the opportunity for extended relief from chronic pain.
Insulet’s OmniPod provides a wearable insulin delivery system in tandem with its Personal Diabetes Manager (PDM). The PDM combines a built-in blood glucose with wireless control of insulin injections administered by the small wearable insulin-delivery pod. Unlike conventional insulin injection systems, the waterproof OmniPod can be worn continuously — even while swimming and showering — without risking noncompliance or compromising an active lifestyle.
Creating a wearable product for medical, health and fitness applications presents new and unique design challenges. Engineers must combine advanced sensor systems, low-power embedded systems and wireless communications into the smallest possible biocompatible packages. At the same time, wearables like wristbands or others likely to be visible must offer the form and fit of an attractive fashion accessory — while still providing extended running time between infrequent charges.
For designers, the challenge becomes one of addressing the conflicting requirements of power and performance. As a result, highly integrated ultra-low-power MCUs typically lie at the heart of wearable designs. These highly integrated MCUs combine on-chip RAM, flash, timers, ADCs and multiple interface options while providing multiple low-power modes featuring only 20 nA in power-down mode. With such low power requirements, energy from the OmniPod’s two AA batteries remains largely reserved for running the relatively power-hungry insulin pump.
For its Shine wearable wireless activity monitor, Misfit faced even greater power constraints. Misfit decided that requiring users to frequently recharge the Shine would interfere with its role as a continuously worn monitor. Consequently, Misfit powers its Shine activity monitor from a user-replaceable CR2032 Li-ion battery expected to provide at least four months of power for a feature-rich wireless application.
With this limited power budget, the Shine must process data from its 3-axis accelerometer using a series of sophisticated algorithms while driving an LED-based user interface and communicating wirelessly with the Shine app on smartphones.
Intel designed its Quark MCU specifically to target wearable and similar deeply embedded applications where low power and small footprint are more critical than raw performance. The initial Quark device, the X1000, integrates a 400MHz 32-bit core with 512KB SRAM, a DDR3 memory controller and multiple connectivity options. Recognising the growing need for security in wearable applications, the X1000 includes an on-chip boot ROM that provides a hardware root of trust used in authentication.
With its Edison development board, Intel provides wearable designers with a very small (SD card form) platform that combines a 400MHz Quark with two cores, LPDDR2 and NAND flash storage and both Wi-Fi and Bluetooth Low Energy (BLE) connectivity.