Flexible Electronics Might Signal New Era of Embeddable Medical Devices

A scientific collaboration between researchers at University of Miami College of Engineering, the University of Illinois at Urbana-Champaign, and Northwestern University, has developed technology to embed electronic circuits into highly flexible materials. Using special “silicon islands” within the material, the researchers claim that can get the fabric to bend up to 140% and twist like a corkscrew up to 90° within 1cm. Because such twisting and bending doesn’t significantly affect the electric properties of the material, we can see this technology being applied for all sorts of implantable medical gadgets.
From the press release:

Potential uses for the new design include electronic devices for eye cameras, smart surgical gloves, body parts, airplane wings, back planes for liquid crystal displays and biomedical devises.
“Our design is of great interest because the requirements for complex shapes that can function during stretching, compression, bending, twisting and other types of extreme mechanical deformation are impossible to satisfy with conventional technology,” said Song.
The secret of the design is in the silicon (Si) islands on which the active devices or circuits are fabricated. The islands form a chemically bonded, pre-strained elastomeric substrate. Releasing the pre-strain causes the metal interconnects of the circuits to buckle and form arc-shaped structures, which accommodate the deformation and make the semiconductor materials much more stretchable, without inducing significant changes in their electrical properties. The design is called noncoplanar mesh design.

More from the article abstract in PNAS:

The use of single crystalline silicon nanomaterials for the semiconductor provides performance in stretchable complementary metal-oxide-semiconductor (CMOS) integrated circuits approaching that of conventional devices with comparable feature sizes formed on silicon wafers. Comprehensive theoretical studies of the mechanics reveal the way in which the structural designs enable these extreme mechanical properties without fracturing the intrinsically brittle active materials or even inducing significant changes in their electrical properties. The results, as demonstrated through electrical measurements of arrays of transistors, CMOS inverters, ring oscillators, and differential amplifiers, suggest a valuable route to high-performance stretchable electronics.

Press release: University of Miami Engineer Designs Stretchable Electronics with a Twist
Abstract in PNAS: Materials and noncoplanar mesh designs for integrated circuits with linear elastic responses to extreme mechanical deformations
Photo: Optical image of a freely deformed stretchable array of complementary metal-oxide semiconductors inverters. Photo Credit: John A. Rogers, University of Illinois at Urbana-Champaign.