Silk optical material
Researchers at the Tufts University School of Engineering and Boston University have fabricated and characterized the first large area metamaterial structures patterned on implantable, bio-compatible silk substrates.
This is a promising path towards the development of a new class of metamaterial-inspired implantable biosensors and biodetectors. The team focused on metamaterial silk composites that are resonant at the terahertz frequency. This is the frequency where many chemical and biological agents show unique “fingerprints,” which could potentially be used for biosensing. The resonance response could be used as an implantable electromagnetic signature for contrast agents or bio-tracking applications.
The researchers conducted a series of in vitro experiments that examined the electromagnetic response of the silk metamaterials when implanted under thin slices of muscle tissue. They found that the metamaterials retained their novel resonance properties while implanted.
“Our approach offers great promise for applications such as in situ bio-sensing with implanted medical devices and the transmission of medical information from within the human body,” says Omenetto. “Imagine the benefits of monitoring the rate of drug delivery from a drug-eluting cardiac stent, making a perfect absorber that can be implanted to attack diseased tissue by heat, or wrapping an ‘invisibility cloak’ around an organ to examine the tissue behind it.”
Tufts University reports that silk hydrogels, films, fibers and sponges are making possible advances in photonics and optics, nanotechnology, electronics, adhesives and microfluidics, as well as engineering of bone and ligaments.
Kaplan and Omenetto believe applications could include degradable and flexible electronic displays for sensors that are biologically and environmentally compatible and implantable optical systems for diagnosis and treatment. Progress in “edible optics” and implantable electronics has already been demonstrated by Kaplan and Omenetto, John Rogers at the University of Illinois at Urbana-Champaign, and others.
Spiders and silkworms generate silk protein fibers that embody strength and beauty. Orb webs are fascinating feats of bioengineering in nature, displaying magnificent architectures while providing essential survival utility for spiders. The unusual combination of high strength and extensibility is a characteristic unavailable to date in synthetic materials yet is attained in nature with a relatively simple protein processed from water. This biological template suggests new directions to emulate in the pursuit of new high-performance, multifunctional materials generated with a green chemistry and processing approach. These bio-inspired and high-technology materials can lead to multifunctional material platforms that integrate with living systems for medical materials and a host of other applications.