The wearables market is one of the fastest growth areas for flexible electronics. However, there are hurdles that have to be overcome for wearables to move on from devices such as fitness trackers and smartwatches to full garments. For example, the garments have to be comfortable, and the flexible electronics practically unnoticeable. eTextiles also have to overcome stretching, folding and washing.
 
UK-based Pireta is making headway in achieving these goals with its patented free-form printed circuit process. In essence, Pireta makes the fabric itself conductive. Ian Russell, chief commercial officer for Pireta, said the company has come a long way since it was spun out of the National Physical Lab (NPL) in the UKin 2017.
 
“Our founder and CTO, Chris Hunt, was leading a team doing research into electronic interconnect technologies, and his team invented a novel process that allows conductive patterns to be added to textiles,” Russell said. “NPL recognized the invention has commercial potential and created a spinout. The company got some funding, and Pireta was set up in 2017; we are working to make the technology more commercial and ready for commercial production.”
 
“We are engaging with customers and potential partners interested in developing eTextiles and wearable products based on our technology,” he added. “Garments that are worn closely to the skin and do some physiological sensing is our sweet spot in markets such as medical, fitness, elite sports and the military.”
 
Russell noted that textiles are not particularly ideal for electronics, but Pireta is overcoming these hurdles.Its technology can be used to create sensors and transducers. It is compatible with RF signals, so NFC, RFID, Bluetooth and Wi-Fi can be built into the eTextiles and smart garments.
 
“Textiles are very challenging substrates to build electronics on as they are highly conformable, foldable and stretchable,” Russell observed. “Building interconnects on top of textiles is real challenging. The key advantage of the Pireta technology is that it makes the textile itself conductive while maintaining the characteristics of the textile itself. You won’t be able to feel the conductive tracks although you can see them.” 
 
Russell said that the fabric would feel like it did originally and stretch as it did originally, adding that this overcomes the limitations of other approaches.
 
“One alternative is printed conductive inks, which are typically an adhesive type substance with conductive particles added to it. This does not bond well to textile substrates so it has to be printed on a plastic layer, and looks like a transfer. It has to be applied on the textile, so it isn’t very stretchable, affects breathability and is not very robust, and can de-bond when it is washed,” Russell said. “The other category is conductive yarns, which can be woven or knitted into the fabric, but this doesn’t allow freeform patterning or flexible interconnects. Conductive yarns are also difficult to scale up.”
 
Pireta has developed a chemical process based on water-based chemistry which can be soldered directly onto the conductive tracks. 
 
“The novel aspect is in the order of the chemical processes,” said Russell. “First, we pretreat the fabric, and then apply the chemical linker. We then print on a nanometal silver catalyst, which defines the pattern. The textile goes through an immersion plating process similar to that of a printed circuit board, and conductive copper material is deposited. Pireta’s technology can be applied roll-to-roll as well as to finished garments. We make sure the performance of the fabric is not impacted.” He added that wash tests have been successful so far.
 
 Russell said that feedback has been really good, and commercialization is close. 
 
“The wearables market in terms of textiles and smart clothing is still at an early stage,” he observed. “No one has hit the killer application yet. People understand why our technology is different and have experienced the limitations of the alternatives, and there is a lot of appreciation for our capabilities. 
 
“It is really gratifying to meet with customers and develop prototypes,” he added. “We are nearing commercialization, and are still at the stage where we are building out our mass production capabilities. We see ourselves being involved in pilot manufacturing and long-term, licensing our technology to multiple companies. We are working with some really interesting customers, from general fashion and apparel, transportation such as for upholstery, healthcare, wellness, elite sports. It is a really interesting time. There are some really interesting ideas out there.”