Engineers at Stanford University have developed a miniature, wirelessly powered implanted device to deliver optogenetics.
What is optogenetics? Essentially it’s the act of using light to control the activity of the brain or other cells of living tissue.
But before anyone starts tossing around words like “mind control,” let it be clarified: Scientists have for some time used optogenetics for research into how to relieve tremors due to Parkinson’s disease and for investigations into possible treatments for strokes.
Nerves must be carefully prepared to contain the proteins necessary for tissue to respond to the light and so untreated neurons are completely immune to the effects. The public need not worry about losing control of their bodies to a comic-book-style supervillain any time soon.
This mouse's body transmits energy to an implantable device that delivers light to stimulate leg nerves in a Stanford optogenetics project. Image courtesy Stanford University.
The new internally-operated device is anticipated to expand the scope of research, allowing test mice to move about more freely and interact naturally with other animals.
The smallest version of the device weighs only 20 mg and is 10 mm3 in size. This is two times smaller than previously reported wireless optogenetic systems.
The Power of Radio Frequency Energy
Ada Poon, assistant professor of electrical engineering at Stanford, said developing the tiny device to deliver light was the easy part.
The real challenge was finding a way to power the device over a large area without compromising efficiency. Poon’s team looked to radio frequency energy for the solution.
Working with bioengineers over at Stanford Bio-X, Stanford’s interdisciplinary biosciences institute, Poon got the idea to use the mouse’s body to transfer the energy at the precise wavelength that it could resonate through a mouse. Initial test results were published on August 4 in Physical Review Applied.
Poon set out to develop a chamber capable of storing and amplifying radio frequency energy with co-authors John Ho, assistant professor at the National University of Singapore and Yuji Tanabe, a research associate.
Visiting Japan, the team collaborated with Tanabe’s father, who had once worked at Stanford’s SLAC research center. A chamber with a grid overlay was soon developed which could trap radio frequency energy.
The grid allowed mice to act as a conduit for the stored energy, which could be released from the chamber and captured by a 2 mm coil in the implanted optogenetics device.
The mice essentially become a localizing device for power delivery.
Advantages of Implanted Optogenetic Devices
As mentioned earlier, standard optogenetic devices can be large and clunky when used with mice.
The big headsets make it difficult for mice to travel through enclosed spaces, making socializing with other mice difficult. Researchers must handle the mice to attach the power cable, which can stress the mice and negatively affect the outcome of the experiment.
Using implantable technology, researchers can enact experiments on mice capable of behaving naturally. This will help researchers better understand and treat mental health disorders, movement disorders and diseases affecting internal organs.
A grant, recently received from Stanford Bio-X, will allow the team to explore new treatments for chronic pain.
The implantable device can be reconfigured for different uses in a lab so the plans for the power source are publicly available. “I think other labs will be able to adapt this for their work,” Poon said.
Poon’s findings have been published in the August 17 edition of Nature Methods.