David Savastano, Editor04.10.19
The world of wearables has changed dramatically since the first wearables were introduced in the early 1980s. Polar Electro, a pioneer of sports wearables, began proving wearable heart rate solutions for customers as far back in 1983.
Dr. Jyrki Schroderus, director of research & technology for Polar Electro, noted that in 1983, the first wearable looked like a wristwatch, and also in the 1980s, there were chest straps for swimming. By the 2000s, Polar started making apparel and web services, and in the 2010s, mobile connectivity was included.
“In the past, sports testing was done with huge equipment,” Dr. Schroderus said. “We found that we could get freedom with wearables – biosensors, wireless connectivity, and wearable user interface.”
Dr. Schroderus observed that there have been huge changes in the technology through the decades, adding that flexible and printed electronics can take wearable technology further than anyone imagined three decades ago.
One of the key advantages of flexible and printed electronics for wearables is the ability to conform to the human body. Rigid items are by nature uncomfortable, and the human body is not flat; people are not inclined to wear something that is uncomfortable. There is also a price advantage.
“Wearables are by default in contact to the human body, and therefore comfort is the key user experience factor,” Dr. Schroderus observed. “Printable structures combined with flexibility enable products such as biosensor wearables, which detect very weak biosignals, to fit easily to the human body and can be worn 24/7. This is very important when tracking human physical activity and sleep. In mass products, printability also provides cost efficiency in production and flexibility to provide size variants for wearables.”
For example, flexible and printed biosensors can be integrated into clothing.
“I think that apparel-type products, such as sports shirts or pants with integrated biosensors, would have a great benefit from printed and flexible electronics,” said Dr. Schroderus. “Printed structures, such as skin electrodes, are relatively large and complex in terms of the layer structure and figurative design, and the manufacturing phase requires plenty of handwork. The size variants of these type of products are essential from the business point of view, and printing may tackle these challenges. Printing techniques are also used when shape-sensitive thin surfaces, such as antenna structures inside wrist watches and sensors, are needed on three-dimensional structures.”
Dr. Schroderus pointed out that Polar is already using flexible and printed electronics. For example, he noted that flexible electronics is a widely used technology to implement electromechanical connections between functional modules, such as the main PWB (Printed Wiring Board) and display, in wristwatches and other devices where the size and shape of the product are critical factors.
“Some functional units, such as LED display modules for example in the Polar Loop activity tracker, also have been implemented with a flexible PWB,” he added. “So we can say that the printed flexible structures are still primarily hidden inside the products and are not visible to the end user in normal use of the product. Of course, one shall not forget that Polar has provided flexible wearables since 1983 when we launched the first wearable heart rate monitor and a wrist unit for athletes. Those days, the printing technique as such was not applied for the biosensor components.”
There are challenges that need to be overcome for flexible and printed electronics to reach mainstream markets.
“When we consider the most challenging products relating to printing and flexibility in consumer products, we often talk about wearable biosensors with skin contact measurement, such as an ECG-based sensor (electrocardiogram) in the sports category,” Dr. Schroderus said. “The requirements relate to electromechanical durability, technical performance, user experience, cost factors, and manufacturability. All factors shall be accounted for simultaneously in order to obtain a successful mass product. So far, we haven’t seen any products on the market that fits all listed requirements.
‘One paradox in the printing technology is that it is primarily targeted to provide large functional surfaces or benefits from mass production of millions of similar products,” he added. “However, the investments to such manufacturing equipment is relatively high, and especially in the sports category, the investment requirement is seldom consistent with the business expectations of the product. Therefore, conventional manufacturing solutions are applied instead. In other words, one bottleneck is also the availability of scalable manufacturing equipment.”
Overall, Dr. Schroderus sees opportunities ahead for flexible and printed electronics for wearables in the next five to 10 years.
“The competition in the sports category will become more intense since the technology availability regarding conventional solutions is improving,” he noted. “Therefore, the most innovative companies, such as Polar Electro, will adopt new innovations in order to improve the functionality, user experience and cost structure of the products. I believe that functional apparel with integrated biosensors will apply printable and flexible structures in five years on a regular basis, and we hope that that the manufacturing technology will evolve to enable that development.”
