Tag Archives: infrared

Wireless nano for remotely activating neurons

Every once in a while, there’s a piece of research that disconcerts me and this would be one of those pieces. From a May 22, 2014 news item on Nanowerk,

Yang Xiang, PhD, assistant professor of neurobiology at University of Massachusetts Medical School, has received a three-year, $900,000 grant from the Human Frontiers Science Program to lead an international team of scientists, including Gang Han, PhD, assistant professor of biochemistry & molecular pharmacology, in the development and implementation of a new optogenetic platform that can remotely activate neurons inside a free-moving organism.

Using a new class of nanoparticles developed by Dr. Han, Dr. Xiang and colleagues propose to selectively turn on non-image forming photoreceptors (NIFP) inside mice and Drosophila unencumbered by the fiber optic wires used in currently available optogenetic technologies. By wirelessly stimulating these photoreceptors, which are able to sense light even though they don’t generate vision, scientists can better understand their role in regulating physiological functions such as circadian rhythm, sleep and melatonin secretion. The hope is that this new technology can also be used to study the links between other types of neurons, physiology and behavior.

A May 22, 2014 University of Massachusetts Medical School news release by Jim Fessenden, which originated the news item, describes optogenetics and some of its challenges,

“Current optogenetic technologies are limited in their application because they require using ‘wired’ fiber optic implants to deliver blue light to activate neuron activities,” said Xiang. “This is a major technological problem that has become an obstacle to understanding the physiological role NIFP play in animal behavior. If we’re able to overcome this hurdle by using the nanoparticles developed by Dr. Han, it would open the door to more informed investigations of not only NIFP but a wide range of neurons and their effect on behavior.”

In use for only about a decade, optogenetic technology combines techniques from optics and genetics, allowing scientists to precisely control activities of individual neurons using light. By genetically inserting light-activated biological molecules such as channelrhodopsins, a family of proteins found in algae, into neurons, scientists can instantaneously turn them on using beams of blue light with millisecond precision.

A limiting factor to the wider application of this technology, however, is that blue wavelengths are unable to penetrate skin, bone and other tissues deep enough to activate the neurons inside free-moving animals. To overcome this obstacle, current techniques require the insertion of fiber optic wires close enough to the neurons so the light that activates them can be delivered. This technique restricts animal movement and makes it difficult to observe behavioral responses in natural conditions. This fiber optic approach further limits scientists’ ability to study behavior over longer periods of time as the effectiveness of light delivery is relatively short due to scarring.

The news release describes the new technique proposed by Xiang and his associates,

Han has developed an “upconversion nanoparticle” (UCNP) that has the potential to solve the limitations of wired optogenetic techniques. These nanoparticles are capable of absorbing infrared light that can’t be seen and converting it into visible blue light. In contrast to blue light, infrared light is capable of penetrating skin and tissue to a depth of several centimeters. Xiang and Han believe these nanoparticles, tuned to emit blue light, can be inserted into the brain and used as a substitute for traditional fiber optics to wirelessly activate neurons in animals.

The hope is that the nanoparticles will absorb infrared light that passes through the tissue, and convert it to blue light inside the animal. This blue light would then activate the NFIPs. If successful, Xiang and colleagues will be able to observe any changes in animal behavior brought about by activating these non-image forming photoreceptors.

“The nanoparticles act as a kind of relay station,” said Han. “They convert the low-energy red light into a high-energy blue light that can activate the neurons. This technique completely alleviates the need to use intrusive fiber optic wires. It vastly simplifies the technology and expands the potential uses for optogenetics.”

Xiang said, “In many ways, this is the perfect bridge between a technological advancement and an important biological question. With these nanoparticles it’s possible for us to begin answering fundamental neurobiological questions about NIFPs.

“More broadly, it would open up the possibility of using other model organisms, such as Drosophila, that can’t be used with the current wired optogenetic technologies, to investigate and answer important questions about how neural activities regulate behavior.”

Illogical as it is, the idea that neurons could be wirelessly and remotely activated by someone other the owner of those neurons disturbs me even though I know drugs are commonly used to do much the same thing in humans.

In any event, the news release provides this final paragraph about the funding,

HFSP [Human Frontiers Science Program] awards are given to highly innovative teams that demonstrate that they have developed and can test a paradigm-shifting idea that holds promise for the development of new approaches to problems in the life sciences with potential to advance the field of research significantly.

I looked up the HFSP online and found this on the About Us page on the HFSP website,

The Human Frontier Science Program is a program of funding for frontier research in the life sciences. It is implemented by the International Human Frontier Science Program Organization (HFSPO) with its office in Strasbourg.

The members of the HFSPO, the so-called Management Supporting Parties (MSPs) are the contributing countries and the European Union, which contributes on behalf of the non-G7 EU members.

The current MSPs are Australia, Canada, France, Germany, India, Italy, Japan, Republic of Korea, Norway, New Zealand, Switzerland the United Kingdom, the United States of America and the European Union. [emphasis mine]

I was not expecting to find Canada on that list.

Better night vision goggles for the military

I remember a military type, a friend who served as a Canadian peacekeeper (Infantry) in the Balkans, describing night-vision goggles and mentioning they are loud. After all, it’s imaging equipment and that requires a power source or, in this case, a source of noise. The Dec. 29, 2012 news item on Nanowerk about improved imaging for night vision goggles doesn’t mention noise but hopefully, the problem has been addressed or mitigated (assuming this technology is meant to be worn),

Through some key breakthroughs in flexible semiconductors, electrical and computer engineering Professor Zhenqiang “Jack” Ma has created two imaging technologies that have potential applications beyond the 21st century battlefield.

With $750,000 in support from the Air Force Office of Scientific Research (AFOSR), Ma has developed curved night-vision goggles using germanium nanomembranes.

The Dec. 28, 2012 University of Wisconsin-Madison news release, which originated the news item, describes the Air Force project and another night vision project for the US Department of Defense,

Creating night-vision goggles with a curved surface allows a wider field of view for pilots, but requires highly photosensitive materials with mechanical bendability-the silicon used in conventional image sensors doesn’t cut it.

…  Ma’s design employs flexible germanium nanomembranes: a transferrable flexible semiconductor that until now has been too challenging to use in imagers due to a high dark current, the background electrical current that flows through photosensitive materials even when they aren’t exposed to light.

“Because of their higher dark current, the image often comes up much noisier on germanium-based imagers,” says Ma. “We solved that problem.”

Ma’s dark current reduction technology has also been recently licensed to Intel.

In another imaging project, the U.S. Department of Defense has provided Ma with $750,000 in support of development of imagers for military surveillance that span multiple spectra, combining infrared and visible light into a single image.

“The reason they are interested in IR is because visible light can be blocked by clouds, dust, smoke,” says Ma. “IR can go through, so simultaneous visible and IR imaging allows them to see everything.”

Inexpensive silicon makes production of visible light imagers a simple task, but IR relies on materials incompatible with silicon.

The current approach involves a sensor for IR images and a sensor for visible light, combining the two images in post-processing, which requires greater computing power and hardware complexity. Instead, Ma will employ a heterogeneous semiconductor nanomembrane, stacking the two incompatible materials in each pixel of the new imager to layer IR and visible images on top of one another in a single image.

The result will be imagers that can seamlessly shift between IR and visible images, allowing the picture to be richer and more quickly utilized for strategic decisionmaking.

It’s impossible to tell from the description if this particular technology will be worn by foot soldiers or human military personnel but, in the event it will be worn,  it does well to remember that it will need a power source. Interestingly, the average soldier already carries a lot of weight in batteries (up to 35 pounds!) as per my May 9, 2012 posting about energy-harvesting textiles and the military.