What if computer technology was to integrate within our bodies? Think of all the possibilities. We could install built-in health monitoring systems as well as technological communication devices. These seemingly far-off advances are exactly what material scientists are currently trying to accomplish.
In a landmark development, researchers have successfully designed electronic interfaces that can be fully implemented into the human body. Dubbed "electronic foils," this invention allows circuits to conform to any surface, giving them the unique ability to adapt to a moving body part. These electronics—which can be stretched, bent, and crumpled—may someday become as common as plastic wrap.1 Wearable technologies have potential applications ranging from medical diagnostics and wound healing to video game control. Electronic skin has been shown to monitor patients' health measurements as effectively as conventional, state-of-the-art electrodes that require bulky pads, straps, and irritating adhesive gels.2
Traditional electronics are hard and unyielding, typically making them unable to serve in biological applications.1 However, developments in materials science are transforming the way we think about electronics. Dr. John Rogers, an engineer at the University of Illinois at Urbana-Champaign, studies the characteristics and applications of "soft materials,” or those without physical restraints. Scientists have engineered “transient electronics,” a new class of electronics that can degrade completely after carrying out a designated task. The potential applications of this technology are impressive. For example, Rogers and his team successfully embedded heat-sensitive, transient circuits into surgical wounds of mice to fight infection. These devices were then absorbed into surrounding tissue after a threshold exposure to biological fluids.3
The secret to transient electronics’ disappearing act lies in their material composition. The circuits implanted in the mice were crafted from sheets of porous silicon and magnesium electrodes packaged in enzymatically-degradable silk. Its solubility in water is programmable thorough the addition of magnesium oxide to create a crystalline structure. By tweaking the framework, researchers can control how quickly the engineered silk dissolves, be it over a matter of seconds or several years.3 Scientists foresee applications in which these devices are placed on a wound or inside the body immediately after surgery, so they can integrate and wirelessly transmit information,1 such as heart rate, blood pressure, and blood oxygen saturation levels.3
Using Roger’s work, Martin Kaltenbrunner, an engineer at the University of Tokyo, discovered how to further expand the applications of flexible electronics and demonstrated a number of uses for their virtually unbreakable circuits. For example, the researchers built a thin transistor incorporated into a tactile sensor that conforms to uneven surfaces. By placing such a device on the roof of a person's mouth, paralyzed patients could give yes or no answers by touching different spots of the sensor. Touch sensitivity could also help those with artificial limbs to gain feeling. Kaltenbrunner’s team also built a mini temperature sensor that adheres to a person's finger. In the future, this simple sensor could be implemented in an imperceptible adhesive bandage for health monitoring.3
The lines between human and machine are becoming blurred. As frightening as seems, the impact of electronic foils on biomedical devices is a positive one. Health monitoring will become commonplace, and the skin can be used as a signal transductor. With the onset of these human-integrable electronics, the field of biomedicine will be completely revolutionized.
- Kaltenbrunner, M. et al. Nature 2013, 499, 458-463.
- Kim, D. et al. Science 2011, 333, 838-843.
- Hwang, S. et al. Science 2012, 337, 1640-1644.