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Helen Schwerdt, Ann Graybiel, Michael Cima, Bob Langer, and MIT colleagues have developed and implantable sensor that can measure dopamine in the brain of rodents for more than one year.  They believe that this can inform the treatment and understanding of Parkinson’s and other brain diseases.

According to Graybiel, “Despite all that is known about dopamine as a crucial signaling molecule in the brain, implicated in neurologic and neuropsychiatric conditions as well as our abilty to learn, it has been impossible to monitor changes in the online release of dopamine over time periods long enough to relate these to clinical conditions.”

The sensors arenearly invisible to the immune system, avoiding scar tissue that would impede accuracy. After  implantation, populations of microglia  and astrocytes were the same as those in brain tissue that did not have the probes.

In a recent animal  study, three to five sensors per were implanted 5 millimeters deep in the striatum. Readings were taken every few weeks, after dopamine release was stimulated in the brainstem, traveling to the striatum. Measurements remained consistent for up to 393 days.

If developed for use in humans, these sensors could be useful for monitoring Parkinson’s patients who receive deep brain stimulation.

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Georgia Tech’s Woon-Hong Yeo has  developed a proof of concept, flexible, stretchable sensor that can continuously monitor hemodynamicswhen integrated with a stent like flow diverter after a brain aneurysm. Blood flow is measured using  capacitance changes.

According to Pittsburgh professor Youngjae Chun, who collaborated with Yeo, “We have developed a highly stretchable, hyper-elastic flow diverter using a highly-porous thin film nitinol,” Chun explained. “None of the existing flow diverters, however, provide quantitative, real-time monitoring of hemodynamics within the sac of cerebral aneurysm. Through the collaboration with Dr. Yeo’s group at Georgia Tech, we have developed a smart flow-diverter system that can actively monitor the flow alterations during and after surgery.”

The goal is a batteryless, wireless device that is extremely stretchable and flexible that can be miniaturized enough to be routed through the tiny and complex blood vessels of the brain and then deployed without damage  According to Yeo, “It’s a very challenging to insert such electronic system into the brain’s narrow and contoured blood vessels.”

The sensor uses a micro-membrane made of two metal layers surrounding a dielectric material, and wraps around the flow diverter. The device is a few hundred nanometers thick, and is produced using nanofabrication and material transfer printing techniques, encapsulated in a soft elastomeric material.

“The membrane is deflected by the flow through the diverter, and depending on the strength of the flow, the velocity difference, the amount of deflection changes,” Yeo explained. “We measure the amount of deflection based on the capacitance change, because the capacitance is inversely proportional to the distance between two metal layers.”

Because the brain’s blood vessels are so small, the flow diverters can be no more than five to ten millimeters long and a few millimeters in diameter. That rules out the use of conventional sensors with rigid and bulky electronic circuits.

“Putting functional materials and circuits into something that size is pretty much impossible right now,” Yeo said. “What we are doing is very challenging based on conventional materials and design strategies.”

The researchers tested three materials for their sensors: gold, magnesium and the nickel-titanium alloy known as nitinol. All can be safely used in the body, but magnesium offers the potential to be dissolved into the bloodstream after it is no longer needed.

The proof-of-principle sensor was connected to a guide wire in the in vitro testing, but Yeo and his colleagues are now working on a wireless version that could be implanted in a living animal model. While implantable sensors are being used clinically to monitor abdominal blood vessels, application in the brain creates significant challenges.

“The sensor has to be completely compressed for placement, so it must be capable of stretching 300 or 400 percent,” said Yeo. “The sensor structure has to be able to endure that kind of handling while being conformable and bending to fit inside the blood vessel.”

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Stanford’s Alberto Salleohas created a  patch that continuously monitors cortisol levels in sweat.  Potential uses include sports performance measurement, early disease detection, adrenal and pituitary gland monitoring, and evaluating the emotional state of young or non verbal patients.

Cortisol influences emotional stress, blood pressure, metabolism, immune response and and memory formation.

The stretchy, rectangular sensor is wrapped around a membrane that specifically binds only to cortisol. It absorbs sweat through holes in the bottom. Sweat pools in a reservoir, topped by the cortisol-sensitive membrane. Charged ions pass through the membrane unless they are blocked by cortisol. The sensor detects the backed up charged ions. The top  waterproof layer protects the patch from contamination.

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University of Illinois professors Bruce Schatzand David Buchnerhave developed a system to predict senior fall risk using motion sensors that measure walking patterns.

67 women over 60 were testedon walking ability,  detailed past annual falls, and wore an accelerometer for one week.

The analysis of device data and reported history enabled the researchers to accurately predict falls based on unsteadiness in standing and walking.

The goal is prevention — encouraging  those who know that they are at risk, and their physicians, to focus on strength and balance exercises.

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Myant‘s Tony Chahine reimagined human presence at ApplySci’s recent Wearable Tech + Digital Health + Neurotech conference at Stanford:

Tony Chahine on human presence, reimagined | ApplySci @ Stanford - YouTube
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