PRINCETON, NJ—Blending electronics and biology, scientists at Princeton University have used readily available 3D printing tools to create a functioning “bionic ear” that can detect radio frequencies far beyond the range of normal human capability.
In a May 1 news release, John Sullivan of the Office of Engineering Communication at Princeton reported that the primary purpose of the researchers was to develop an effective means of merging electronics with biological tissue. The scientists used 3D printing of cells and nanoparticles followed by cell culture to combine a small coil antenna with cartilage, creating what they termed a bionic ear.
The lead researcher is Michael McAlpine, an assistant professor of mechanical and aerospace engineering at Princeton. He told Sullivan, “There are mechanical and thermal challenges with interfacing electronic materials with biological materials. However, our work suggests a new approach–to build and grow the biology up with the electronics synergistically and in a 3D interwoven format.”
The Princeton team has been doing research in cybernetics for several years. This promising field seeks to design bionic organs and devices to enhance human abilities. The bionic ear project was the first effort by McAlpine and colleagues to create a fully functional organ: one that replicates a human ability and then uses embedded electronics to extend it.
Writing in the journal Nano Letters, the scientists said that cybernetics, “has the potential to generate customized replacement parts for the human body, or even create organs containing capabilities beyond what human biology ordinarily provides.”
In order to replicate complex three-dimensional biological structures, the researchers turned to 3D printing. A 3D printer uses computer-assisted design to conceive of objects as arrays of thin slices. It then deposits layers of materials to build up a finished product.
One example of this approach is CAMISHA (computer-aided-manufacturing-for-individual-shells-for-hearing-aids), which was invented by Soren Westermann at Widex, and is now used to build 95% of custom hearing aids.
According to Princeton, the bionic ear project marked the first time that researchers have demonstrated that 3D printing is a convenient strategy to interweave tissue with electronics. The researchers used an ordinary 3D printer to combine a matrix of hydrogel and calf cells with silver nanoparticles that form an antenna. The calf cells later develop into cartilage.
The initial device developed by McAlpine and colleagues detects radio waves, but the team plans to incorporate other materials that would enable it to hear acoustic sounds. While it will take much more work to develop a bionic ear that could restore or enhance human hearing, McAlpine said that in principle it should be possible to do so.
The team that developed the bionic ear consists of six Princeton faculty members, two graduate students from Princeton and Johns Hopkins University, and Ziwen Jiang, a high school student at the Peddie School in Hightstown, NJ. McAlpine said of the precocious teenager, “We would not have been able to complete this project without him, particularly in his skill at mastering CAD designs of the bionic ears.”