Manufacturing Bits: July 18

Brain microscopes; neuro imaging; measuring kilograms.

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Brain microscopes
Rice University is developing a tiny and flat microscope for a special application–it will be able to decode and trigger neurons on the surface of the brain.

The microscope technology, dubbed FlatScope, is part of a $65 million program announced by the U.S.-based Defense Advanced Research Projects Agency (DARPA). The DARPA project, dubbed Neural Engineering System Design (NESD) program, hopes to develop a next-generation high-resolution neural interface.

Lab prototype of a flat microscope (Source: Rice)

The idea is to provide an alternate path for delivering sight and sound to the brain. Researchers hope to gain more insights into vision, hearing and speech. It could one day lead to new treatments for people with sensory deficits.

Meanwhile, today’s probes that monitor and deliver signals to neurons are limited, according to researchers from Rice. To address the issue, Rice is developing a flat microscope for neuron research that is a revolutionary step from a previous effort.

In 2015, Rice developed a technology called FlatCam, a tiny and thin camera. The device is a thin sensor chip with a mask. It replaces a lens in a traditional camera.

In the new project, Rice plans to make the FlatCam flatter. The device would sit between the skull and cortex. It would have the ability to sense and deliver signals from millions of neurons to a computer. “The microscope we’re building captures three-dimensional images, so we’ll be able to see not only the surface but also to a certain depth below,” said Ashok Veeraraghavan, a researcher at Rice, on the university’s Web site. “At the moment we don’t know the limit, but we hope we can see 500 microns deep in tissue.”

Rice researcher Caleb Kemere added: “That should get us to the dense layers of cortex where we think most of the computations are actually happening, where the neurons connect to each other.”

Neuro imaging
Institut Fresnel has developed a metrology technique that could provide new insights into neurodegenerative diseases like Alzheimer’s disease and multiple sclerosis, according to a report from The Optical Society (OSA).

The technique is called high-speed polarization resolved coherent Raman scattering imaging. This technique reveals the chemical makeup and molecules in a sample, according to the OSA, which added the data can be used to understand the behavior of molecules.

Raman scattering detects signals when light interacts with molecules. Researchers improved the technique by modulating the laser light’s power. It also acquires information in mere seconds. “We designed a technique able to image molecular organization in cells and tissues that can ultimately let us see the early stage of this detachment and how lipids are organized within this myelin sheath,” said Sophie Brasselet of the Institut Fresnel on the OSA Web site. “This could help us understand the progression of diseases by identifying the stage at which lipids start disorganizing, for example, and what molecular changes are occurring during this time. This could allow new targeted drug treatments that work differently than those used now.

“We took the concept of intensity modulation used for stimulated Raman scattering and transposed it to polarization modulation using an off-the-shelf device,” said Brasselet. “The signal detection for our technique is very similar to what is done with stimulated Raman scattering, except that instead of detecting only the intensity of the light, we detect polarization information that tells us if molecules are highly oriented or totally disorganized.”

Measuring kilograms
Using a measurement technique, the National Institute of Standards and Technology (NIST) has made its most precise determination of Planck’s constant.

This, in turn, is a big and ongoing step to redefine the kilogram. The kilogram is one of several units defined by the International System of Units (SI). Originally defined in 1875, the kilogram is the only SI unit that is still described as an artifact rather than a fundamental physical property.

In 2011, the General Conference on Weights and Measures approved a plan to redefine the kilogram and other measurement units. The new definition for the kilogram will be based on the fixed numerical values of Planck’s constant (h).

Several organizations have developed techniques to measure Planck’s constant. For example, NIST uses an instrument known as the Kibble balance. Once called a watt balance, the Kibble balance uses electromagnetic forces to balance a kilogram mass. With the technology, NIST’s measurement of Planck’s constant is 6.626069934 x 10−34 kg∙m2/s with an uncertainty of 13 parts per billion. NIST’s previous measurement, published in 2016, had an uncertainty of 34 parts per billion.

NIST’s Kibble balance (Source: NIST)