IoT Needs To Get More Flexible

Republished guest column from EETimes.

By Wilfried Bair, NextFlex

Flexible hybrid electronics can deliver much of what is promised for the future world of the Internet of Things.

Startups and major corporations alike are collaborating to bring to market flexible, conformable and stretchable form factors that truly enable smart everything. Efforts are under way to build an ecosystem of partners, suppliers and a workforce necessary to grow and sustain the infrastructure in the U.S. for such flexible hybrid electronics (FHE).

FHE is the combination of two concepts. Flexible electronics, in volume production today, are based on a flexible circuit boards using subtractive manufacturing methods with active and passive components attached. Printed electronics involve printing conductors as well as active components on flexible substrates and is used today for RFID tags and smart cards.

FHE combines flexible substrates with the low cost of printed electronics and silicon-based ICs. This combination creates unique low-cost, lightweight and powerful ultra-thin electronic devices that can conform to any surface.

An FHE smart patch. (Image: Air Force Research Laboratory)

The picture above shows one example of a flexible printed substrate with an integrated IC. Combining additive manufacturing and novel materials with bare silicon die reduces cost and size and creates devices adaptable to various surfaces.

Most IoT concepts have yet to be realized in volume production due in part to the lack of inexpensive, mass-distributed sensor systems. FHE is well positioned to fill the gap for many industrial, medical, automotive and consumer applications.

The requirements for FHE include:

• Printing conductors on flexible substrates
• Printing sensors or passive elements
• Placing and mechanically and electrically integrating bare die
• Placing and mechanically and electrically integrating passives

The image at the bottom of the page shows an example of a smart wound patch. This health and performance monitoring system is now under development by NextFlex.

A closed-loop sensing system monitors the oxygen levels in a wound and releases oxygen at levels required for optimal healing. A control system connected to the smart wound dressing monitors the sensor parameters and controls the release of drugs. Data collection of drug release and wound condition are wirelessly transmitted through a low-power Bluetooth system.

This example uses flexible materials for the wound dressing, while the control system is based on a rigid board and casing design. Moving this design to the market will require redesigning the rigid control module and deploying it on an FHE platform to reduce size and weight and offer conformal and stretchable properties for the patient applying the wound dressing to the body.

Taking a prototype system such as the one described here into high-volume manufacturing requires characterization and selection of materials suitable to meet production requirements. It also needs a supply chain for all materials required in the manufacturing process.

–Wilfried Bair is a senior engineering manager responsible for device integration and system-level hardware projects at NextFlex.

This smart wound patch is in development by a team drawn from Purdue University, Indiana University, Integra LifeSciences, and Western Michigan University who provided the image.