See-Through Sensors for Better Brain Implants

Graphene electronics are flexible and transparent enough to improve light-triggered brain control technique

2 min read
See-Through Sensors for Better Brain Implants
Photo: Justin Williams Research Group

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Brain scientists first discovered how to use light to remotely control genetically-modified brain cells about a decade agoa breakthrough that has enabled new scientific studies of depression, addiction and Parkinson’s disease. Now a new generation of transparent brain sensors could record brain cell responses without blocking the light’s access to the underlying brain tissue.

The brain control technique that seems to hearken from science fiction, called optogenetics, has traditionally relied on metallic sensors sitting on the surface of the brain to record the organ’s responses to the light stimulation. Some transparent versions of the brain implants have tried electrodes made of indium-tin oxide, a brittle material that is ill-suited to the idea of flexible brain sensors and has limited transparency for certain wavelengths of light. In a study published this week in  Nature Communications, a team of U.S. researchers working with a Thai colleague have shown how sensors made from graphene could work much better.

A traditional implant looks like a square of dots, and you can't see anything under it,” said Justin Williams, a professor of biomedical engineering and neurological surgery at the University of Wisconsin-Madison, in a press release. “We wanted to make a transparent electronic device."

The new device mainly consists of four layers of graphene—each layer just one atom thick—sandwiched between two layers of moisture-proof polymer. Researchers had to strike a balance between having better conductivity with increasing material thickness and having better transparency with a greater thinness. Thinness also helps give the new device its flexibility so that the sensors can adjust to the surface of the brain.

A thin graphene arrangement allowed more than 90 percent of light—from the ultraviolet to infrared—to pass through. By comparison, sensors made from indium-tin oxide allowed 80 percent of light through; traditional sensors made from thin metallic materials allowed just 60 percent . Researchers tested the brain devices by surgically implanting them in lab rats and mice. 

Other implantable microdevices might be transparent at one wavelength, but not at others, or they lose their properties,” said Zhenqiang (Jack) Ma, a professor of electrical and computer engineering at UW-Madison, in the press release. “Our devices are transparent across a large spectrum... We’ve even implanted them and you cannot find them in an MR scan.”

Such transparency should give a boost to optogenetics studies, which have already shown a remarkable ability to control the brain. One of the latest studies looked at using lasers to transform bad memories into good memories in mice.

The new transparent sensors should also be compatible with a wide range of brain imaging techniques that rely on various light wavelengths. That’s crucial for medical researchers trying to understand how new electromagnetic or drug treatments can help patients with brain-related diseases such as epilepsy or Parkinson’s disease.

Transparent sensors could also spawn a wide variety of other medical uses. For instance, the UW-Madison team is working with the University of Illinois-Chicago on putting the transparent sensors on contact lenses as a way of monitoring retinal damage or diagnosing glaucoma early on.

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This CAD Program Can Design New Organisms

Genetic engineers have a powerful new tool to write and edit DNA code

11 min read
A photo showing machinery in a lab

Foundries such as the Edinburgh Genome Foundry assemble fragments of synthetic DNA and send them to labs for testing in cells.

Edinburgh Genome Foundry, University of Edinburgh

In the next decade, medical science may finally advance cures for some of the most complex diseases that plague humanity. Many diseases are caused by mutations in the human genome, which can either be inherited from our parents (such as in cystic fibrosis), or acquired during life, such as most types of cancer. For some of these conditions, medical researchers have identified the exact mutations that lead to disease; but in many more, they're still seeking answers. And without understanding the cause of a problem, it's pretty tough to find a cure.

We believe that a key enabling technology in this quest is a computer-aided design (CAD) program for genome editing, which our organization is launching this week at the Genome Project-write (GP-write) conference.

With this CAD program, medical researchers will be able to quickly design hundreds of different genomes with any combination of mutations and send the genetic code to a company that manufactures strings of DNA. Those fragments of synthesized DNA can then be sent to a foundry for assembly, and finally to a lab where the designed genomes can be tested in cells. Based on how the cells grow, researchers can use the CAD program to iterate with a new batch of redesigned genomes, sharing data for collaborative efforts. Enabling fast redesign of thousands of variants can only be achieved through automation; at that scale, researchers just might identify the combinations of mutations that are causing genetic diseases. This is the first critical R&D step toward finding cures.

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