The field of flexible and printed electronics has been seen as having the potential to change the world we live in, but the challenge has been to actually print the product in its entirety.

Industry and researchers realize that flexible hybrid electronics have the ability to be a game changer by using a combination of traditional silicon-based electronics and printed systems.

This has opened a door to new processes and projects.

The formation of NextFlex has been a benefit to the rapidly expanding field. Formed in 2015 through a cooperative agreement between the US Department of Defense ( DoD ) and FlexTech Alliance, NextFlex is a consortium of companies, academic institutions, nonprofits and governments with the goal of advancing US manufacturing of flexible hybrid electronics.

NextFlex executive director Malcolm Thompson said that the mission of NextFlex is to develop and help make a robust manufacturing supply chain and ecosystem for flexible hybrid electronics (FHE). Since its beginnings last November, NextFlex is growing rapidly.

“Our first member signed up in November, and our membership is now up to 58, with approximately 25 more organizations in the pipeline,” Thompson reported. “We have companies that are very interested in a narrow aspect of developing a particular material or piece of equipment, as well as manufacturing companies like Flex and Jabil. We have a whole range of different kinds of companies, from big companies from Boeing, Lockheed, GE and DuPont to very small companies and startups.”

Dan Gamota, VP of the Hardware Innovation Group at Jabil Circuits, said that unlimited product form factor freedom and the ability to deform (bend, twist, and stretch) the product are key differentiators for flexible hybrid electronics.

“Electronics had historically been rigid and put into a rigid housing, but many advanced FHE systems can take infinite shapes by being deformed (twisting and stretching) and ultimately taking the shape of the housing, “ Gamota said. “These FHE systems can conform to the human body or onto 3D structures while providing ancillary functionality, which is a major benefit.”

Gamota said that the hybrid nature of FHE opens up many more product design and functionality opportunities.

“In the early 1990s, printed electronics came on as a 5-cent solution for RFID , but it was never achieved,” Gamota recalled. “A few years later companies were going to print flexible displays, and it never happened. With FHE, we can take a product that already exists or one that is an idea and design a novel wearable product that provides unique functionality that previously was not realized.”

Gamota discussed the example of feeding tubes that are on the market today that were improved through the use of flexible hybrid electronics.

“Objects are being improved because of added functionality by adding FHE,” he said. “One product is a feeding tube, which has been around for 30 years. Its function is to help deliver nutrients into a person’s body more efficiently. It was improved using FHE by integrating a tiny camera at the end of the tube, plus two LEDs that can provide lighting so the healthcare provider can visually inspect the inside of their patient’s stomach. A flexible substrate is needed because it must pass through the patients nose during insertion. That is a product that is commercial today that was realized with the advancement in FHE.”

Stan Farnsworth, VP of marketing for NovaCentrix, said that hybrid printing combines the positive attributes of each technology type.

“For the flexible/printed technologies, which have been in development for decades and are now at a fairly advanced state, direct benefits often include simplified manufacturing methods, more efficient use of materials and allowance for novel form factors,” Farnsworth said. “Benefits achieved by utilizing elements of more traditional electronics technologies include higher electrical performance, reduced cost of components and ability to utilize existing industrial know-how and infrastructure. By combining the right attributes of each technology set, business value can be created through novel product concepts as well as through next-step product iterations.”

Projects for NextFlex

Recently, NextFlex announced its first round of projects utilizing flexible hybrid electronics.

“We put out project calls, which ask for people to address these issues, and the working groups use a selection process,” Thompson added. “Our first range of project calls was fairly broadly based, and we received 71 responses, which was pretty impressive. These projects are really good.”

“Our second project call was narrowed to eight different disciplines and we got very good, specific responses,” Thompson noted. “We are in the process of signing development agreements with the organizations involved.”

PARC, a Xerox Company, and University of California at San Diego have a project ongoing for NextFlex that is creating a mouth-guard biosensor label that can be worn by members of the military and others in high-stress positions. This project, which began under the NanoBio Manufacturing Consortium, monitors lactate concentration, a key indicator of fatigue. The sensors will be printed, and can be adapted to other biomarkers such as sweat.

“We are developing electrochemical enzyme-based sensors using saliva to monitor glucose and lactate, and this is also relevant to other biomarkers like sweat,” Janos Veres, the leader of PARC’s Novel and Printed Electronics Program, said. “There are 180-plus biomarkers in sweat. UC-San Diego is very strong in this field, as they understand the physiology behind biomarkers, and we can make these sensors more amenable to production. We want to make it look like a plastic mouthguard.”

Purdue University, Integra Life Sciences, Western Michigan University and Indiana University School of Medicine are collaborating on a project that can deliver topical oxygen to chronic/non-healing wounds such as diabetic foot and bed sores through a patch. It can be loosely described as a Band-Aid that would be able to convert hydrogen peroxide to oxygen and deliver it specifically to the wound.

“Our project is designed for oxygen-deprived wounds,” said Babak Ziaie, professor of Electrical and Computer Engineering and Biomedical Engineering at Purdue University. “It is a smart wound dressing that delivers oxygen in situ. We are working with Integra to see if we can integrate this into their collagen-based system to improve the healing process. This would provide more functionality if these could be married together.”

Ziaie noted that the project’s focus is on the delivery side. “We convert hydrogen peroxide to oxygen, which would be good for chronic wound care such as diabetes wounds,” he said. “It is low cost, very accurate and delivers to a very specific location. The challenges are manufacturing to scale and to integrate biomaterial with paper and other sensing materials, and how to go all the way to market with FDA approval.”

Ziaie noted that Integra’s expertise in artificial skin is a key to this project.

“Integra is prominent in the artificial skin market,” said Ziaie. “We have a lot of experience in sensors and delivery systems, and we are working on delivering oxygen for chronic wounds using paper and flexible platforms. We have done a lot of work on small scale. Western Michigan is helping us to develop the processes to scale this up, and Indiana University is working on the bio-compatibility of the materials and functionality.”

“We have been working in the field of flexible hybrid electronics for the past three or four years,” Ali Shakouri, Mary Jo and Robert L. Kirk Director, professor of Electrical and Computer Engineering at Purdue University, noted. “The effort at Purdue is focused on applications related to healthcare, ag, food and pharmacy. With the advent of flexible and large area electronics and low cost sensors, it is possible to bring some of the functionality of electronics for applications in food sensors, precision agriculture and smart pharmaceuticals.”

California Polytechnic State University (Cal Poly), together with Jabil Circuit, DuPont and NovaCentrix, are developing digital tattoos. Dr. Jianbiao John Pan, professor and graduate coordinator in the Department of Industrial and Manufacturing Engineering at Cal Poly, noted that the university has worked extensively on printed electronics.

“We are leading a project about developing assembly process and reliability evaluation for attaching ultra-thin silicon ICs onto printed flexible substrates for human monitoring systems,” said Dr. Pan. “One objective is to develop and quantify assembly processes for integrating flexible ICs and sensors onto textiles. We are developing processes that can be transitioned to volume manufacturing quickly.

“We hope to complete our project by the third quarter of 2017, and we believe our assembly process could make many more application-oriented flexible hybrid electronics projects feasible,” Dr. Pan concluded. “These products could change people’s lives, and make human life much better from infants to elderly people.”

“I’m enjoying working with the team at Cal Poly for their creativity and their ability to just get things done, plus I really think the students play a crucial role in the near-term and long-term success of these efforts in a big-picture kind of way,” said Farnsworth. “Jabil brings an incredibly deep history of electronics innovation and manufacturing, and certainly provides an essential voice of reason and pragmatism to the project. DuPont is well-known for materials innovation. At NovaCentrix, we have been focused on developing enabling manufacturing tooling, especially around our PulseForge photonic curing tools, as well as with innovative materials. We’ve also worked hard to develop an integration competency, for how the involved technologies can come together and be made to form a product solution.”

“Our NextFlex project will lead to the design and assembly of FHE-based digital tattoos,” Gamota said. “These tattoos could monitor a variety of biophysical markers, each tattoo having a different sensor for a specific physiological marker. Our partners have come together to establish processes, designs and equipment platforms to develop novel digital tattoos. DuPont is providing the substrate and NovaCentrix the conductive materials, equipment and processing equipment. Cal Poly is conducting the theoretical work and characterization studies, and Jabil is providing the design for manufacturing discipline necessary for industrialization of the product.”

Opportunities for Flexible Hybrid Electronics

The hybrid flexible and printed electronics field has evolved through the years as markets have emerged.

“For a while, the industry was very excited about making flexible displays, but it is not happening as there is an established infrastructure is in place,” said Veres. “A bunch of companies were excited about printable RFID, but it was against an incumbent technology and people realized the limitations of organic semiconductor materials. It didn’t make sense to compete with silicon to make microchips.

“This led to initiatives in simpler areas like touch displays and smart labels , and with the rise or wearables, we are realizing that you can bring silicon into the infrastructure,” Veres added. “We are very interested in the smart label space due to its simplicity. Printing gives the ability to configure different variations. These smart labels can be simple, with one communication chip, one sensor and an antenna . Wearables are coming, and we will grow our understanding and develop more and more dedicated chips and high quality inks and material sets and choose the form factor of the wearables.

“The future deployment of IoT will be very much changing, with intelligence built all around you, from surfaces of cars to the coffee mug in your kitchen,” Veres concluded. “We will need lots of different deployments, some short-lived like smart labels, which may only be needed for a couple of hours.”

Dr. Pan of Cal Poly noted that the flexible electronics industry is still at an early stage.

“We have a lot of knowledge and skills from microelectronics packaging to learn from,” Dr. Pan added. “There are a lot of promising markets, such as human performance monitoring systems, in which we can monitor a patient’s health from a young baby to a patient who has suffered a heart attack. We can eliminate many wires with traces printed on fabric, which allows the patient to be more comfortable. Another big market is athletics, as the coach can monitor athletes for dehydration or exhaustion.”

Gamota believes the potential applications are practically endless.
 
“At Jabil, we see FHE used in products such as mobile communications devices or HMIs (human-machine interfaces) like touch screens on white goods, medical devices, and automotive & aerospace control panels.,” Gamota added. “Flexible hybrid electronics are used in control panels because you don’t want them to be flat, as multi-dimensional surface curvature is visually appealing. HMI is a big one for car instrumentation, home appliances and medical & technical instruments.”
   
“These products are going to continue evolving with novel ideas and unique proof of concepts that are going to provide designers with alternative materials to realize products that have never existed,” Gamota said.
   
“For the most immersive high fidelity audio and extreme resolution video experience, I truly believe that you will have a flexible, stretchable FHE enabled system that has the functionality that you desire and form factor that will allow you to convert it into something that has a big enough field of view but can be small enough that it is not too cumbersome to transport easily,” said Gamota.

“Materials science is now spurring growth into brand new categories of products,” said Gamota. “These might be digital tattoos, where we can make a product that is intimately in contact with your skin using truly stretchable materials. This material allows you to have electronic sensors that maintain contact with your body during deformation and motion to measure physiological conditions.

“I’m most excited about the stretchable part,” Gamota added. “Our imagination can go wild. Sensors on your body could monitor electrolytes, and you can have a specially formulated drink to replenish your electrolytes. Individuals requiring medical oversight can receive point of care service continually with a FHE-based product that provides real-time monitoring.”