The decade of the sensor
What are nonwoven-based hygiene and medical disposables likely to be able to do next?
Quite a lot, if the fast-growing wearable technology industry has anything to do with it!
All predictions say the market for connected health devices will explode over the next decade, and new disposable devices which will sit next to existing absorbent hygiene and medical products on retail shelves are already coming to market.
eSkin
One example is the eSkin Thermometer, developed by the Californian company VivaLnk – a simple and effective stick-on patch for measuring and remotely monitoring the body temperature of sleeping infants.
VivaLnk’s eSkin technology houses complex electronic circuitry, with tiny embedded sensors, in a thin and flexible material which adheres comfortably to the skin. The electronic patch takes its highly accurate temperature readings without requiring a battery.
It works with a smartphone, is extremely easy to use and, since it looks like a colourful plaster, it helps to alleviate any anxiety which may be associated with taking temperatures.
Drug diffusion
French company Feeligreen is introducing new medical patches which actively diffuse drugs through the skin in an ionized form. Known as active iontopheresis, a direct electrical current causes ions of a soluble substance to move across the surface of the skin and diffuse into the underlying epidermis and dermis.
Measuring about 20mm x 20mm and just a couple of millimetres thick, the compact electronic module inside the Feeligreen dermoPatch is layered on top of a flexible printed electronics plaster with electrodes in place, which doubles as the drug gel carrier.
This transdermic drug delivery platform has been proven to speed up drug diffusion for applications including both controlled pain relief and wound healing.
Diabetes
Disposable glucose test strips have already improved the lives of millions of diabetic patients who need to monitor their blood glucose levels on a regular basis.
The new FreeStyle Libre flash glucose-sensing technology from Abbott Diabetes, however, eliminates the need for users to routinely prick their fingers by reading glucose levels through a sensor that can be worn on the back of the upper arm for up to 14 days.
The FreeStyle Libre system consists of a small, round sensor based on wired enzyme technology. Approximately the size of a €2 coin, it is worn on the back of the upper arm and measures glucose every minute through a small filament that is inserted just under the skin and held in place with an adhesive pad.
Fever alarm
Over in Japan, the Takao Someya Organic Transistor Lab at the University of Tokyo recently announced the development of the world’s lightest and thinnest flexible sensor system.
A follow-on from this is the “fever alarm armband” – a flexible, self-powered wearable device, that sounds an alarm if a patient’s body temperature becomes too high.
Such devices have the potential to cut significantly the costs of effective monitoring in hospitals and care homes and this appears to be the simplest solution to date.
The flexible organic components developed for this device are well-suited to wearable devices that continuously monitor vital signs, including temperature and heart rate, for applications in healthcare settings.
Sensors for such applications need to be flexible and wireless for patient comfort, as well as being maintenance-free and independent of an external energy supply. They also need to be cheap enough to allow them to be disposable in order to maintain hygiene standards. Conventional sensors based on rigid components are unable to meet these requirements, so the researchers have developed a flexible solution that incorporates organic components that can be printed with an inkjet printer on a polymeric film.
The fever alarm armband is the first organic circuit which is able to produce a sound output, and also the first to incorporate an organic power supply circuit. The former enables the device to provide audible information when the flexible thermal sensor detects a pre-set value within the ranges of 36.5 ºC to 38.5 ºC, while the latter increases the range of operational illumination by 7.3 times in indoor lighting conditions.
Holst Centre
“Nonwoven fabrics are highly promising materials for medical skin-worn products containing sensors and electronics and for any thermoformable object for which shape is introduced with heat and pressure,” says Margreet de Kok, senior scientist at the Holst Centre, located in Eindhoven in the Netherlands.
This independent R&D institute, founded in 2005, now has 190 researchers working on enabling technologies for flexible electronics and wireless autonomous microsystems, in close collaboration with leading industrial partners all along the value chain.
Work at Holst has included building-up materials that are capable of sensing and actuating over large surface areas via printed electronics and additive manufacturing.
Using these technologies, the resulting products – which are extremely thin and conform to the body – can be produced extremely cost effectively. In concrete applications for the technology, a low cost and wireless multi-sensor health patch has already been developed.
Another key area of focus at the Holst Centre has been on the development of stretchable electronics from which a wrist-based phototherapy device for pain relief has resulted. Consisting of a fully integrated package of LEDs and passive elements on foil, it is highly conformable to the hand and, because it is embedded in silicone, wear comfort and washability are ensured.
“The integration of electronics into materials and objects that have not been functionalised before opens up extensive possibilities,” says Margreet de Kok. “By adding intelligence and/or operating power to materials in close skin contact such as clothing, furniture or bandages, the health of people can be monitored effectively or even improved.”
Automatic diapers
“We’ll see even better sensing devices soon – not just in medical products, but also in the absorbent hygiene market,” says consultant Carlos Richer, who runs the popular Disposable Diaper Network. “Examples include diapers that will alert parents just before a leak and not when the diaper is already wet. Another sensor will prevent the diaper rashes that are associated with the internal chemistry of the liquids in the core.
“We’ll also soon see adult diapers with built-in ‘diuresis indicators’ – designed to help measure the amount of urine inside the diaper, making it easier for nurses. For those patients who are bedridden, we may also see disposable diapers that will dry themselves automatically. The sky’s the limit.”
Expect plenty of surprises from this growing field at the next edition of INDEX – the world-leading nonwovens show which takes place at Palexpo from 4th-7th April 2017.
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