System Bits: Jan. 24

Sensors detect single molecules; awakening graphene; software engineering for good.


Modified carbon nanotubes used to track individual cells
Carbon nanotubes come to the forefront of scientific research yet again, this time for serving as the most sensitive molecular sensing platforms available.

MIT engineers believe they have designed sensors that, for the first time, can detect single protein molecules as they are secreted by cells or even a single cell. The sensors that consist of chemically modified carbon nanotubes could help scientists with any application that requires detecting very small amounts of protein, such as tracking viral infection, monitoring cells’ manufacturing of useful proteins, or revealing food contamination, the team said.

MIT chemical engineers have developed arrays of carbon nanotube sensors that can detect single protein molecules as they are secreted from cells. (Source: MIT)

MIT chemical engineers have developed arrays of carbon nanotube sensors that can detect single protein molecules as they are secreted from cells. (Source: MIT)

Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT said they hope to use sensor arrays like this to look for the ‘needle in a haystack since these arrays represent the most sensitive molecular sensing platforms that we have available to us technologically. “You can functionalize them so you can see the stochastic fluctuations of single molecules binding to them.”

Strano’s lab previously developed sensors that can detect many types of molecules, all based on modifications of carbon nanotubes — hollow, nanometer-thick cylinders made of carbon that naturally fluoresce when exposed to laser light. To turn the nanotubes into sensors, Strano’s lab coats them with DNA, proteins, or other molecules that can bind to a specific target. When the target is bound, the nanotubes’ fluorescence changes in a measurable way.

In this case, the researchers used chains of DNA called aptamers to coat the carbon nanotubes. Previous efforts to use DNA aptamers have been stymied because of the difficulty of getting the aptamer to stick to the nanotube while maintaining the configuration it needs to bind to its target.

Landry overcame this challenge by adding a “spacer” sequence between the section of the aptamer that attaches to the nanotube and the section that binds to the target, allowing each region the freedom to perform its own function.

In the pharmaceutical realm, these sensors are expected to be used to test cells engineered to help treat disease. Many researchers are now working on an approach where doctors would remove a patient’s own cells, engineer them to express a therapeutic protein, and place them back in the patient. These nanosensor arrays could be useful tools for measuring these precious cells and making sure that they’re performing the way they should.

Awakening graphene’s sleeping superconductivity
University of Cambridge researchers have found a way to activate the innate ability of graphene to superconduct, previously dormant.

It has long been postulated that graphene should undergo a superconducting transition, but can’t, the researchers reminded. The idea of this experiment was, if graphene could be coupled to a superconductor, could that intrinsic superconductivity be switched on?

Now, they have found a way to trigger the innate, but previously hidden, ability of graphene to act as a superconductor – meaning that it can be made to carry an electrical current with zero resistance.

The finding further enhances the potential of graphene, which is already widely seen as a material that could revolutionize industries such as healthcare and electronics. Graphene is a 2D sheet of carbon atoms and combines several remarkable properties; for example, it is very strong, but also light and flexible, and highly conductive.

Since its discovery in 2004, scientists have speculated that graphene may also have the capacity to be a superconductor. Until now, superconductivity in graphene has only been achieved by doping it with, or by placing it on, a superconducting material – a process which can compromise some of its other properties.

But in the new work, the researchers managed to activate the dormant potential for graphene to superconduct in its own right. This was achieved by coupling it with a material called praseodymium cerium copper oxide (PCCO).

Superconductors are already used in numerous applications. Because they generate large magnetic fields they are an essential component in MRI scanners and levitating trains. They could also be used to make energy-efficient power lines and devices capable of storing energy for millions of years, they said.

Superconducting graphene opens up even more possibilities. For example, that graphene could now be used to create new types of superconducting quantum devices for high-speed computing. Intriguingly, it might also be used to prove the existence of a mysterious form of superconductivity known as “p-wave” superconductivity, which academics have been struggling to verify for more than 20 years.

Engineering students create tech for blind teen
In an effort to help open up the world to the visually impaired community, a blind teen — India West — worked with students at the University of Michigan to develop technologies to make life easier for the visually impaired.

Once a week last semester, West traveled from Clonlara Academy in Ann Arbor to David Chesney’s Software Engineering class, EECS 481, a senior-level course on U-M’s North Campus.

Chesney, an instructor in computer science and engineering, is known around campus for his Gaming for the Greater Good initiative. For nearly a decade, he’s been combining video game development, software engineering, and altruism—teaching his students to use their skills to benefit diverse populations, the university said.

At first, students focused solely on video game development, but several years ago, he expanded the scope. Now, each semester they work with groups of children or individuals with disabilities to make technologies tailored to meet their needs. Chesney has involved people with autism, cerebral palsy, Bell’s palsy and now visual impairment. He and his students see those who agree to work them as clients.

West had come to the initial class with some ideas for the students: A talking oven. A smart grocery cart that would tell you where you are in a store. A way to know where her friends are sitting in a busy lunchroom.
Given the class’s constraints, those weren’t ideas they could bring to life. But the students listened to West’s experiences and came up with their own solutions to some of her day-to-day difficulties.

Noah Duchan and his group made Smart Shelf, a talking piece of furniture that can tell West what’s on it and where, and also describe the location of open areas. To build it, they linked a Raspberry Pi computer, an Amazon’s Echo smart speaker and an Amazon Alexa intelligent personal assistant.

Many of the teams will be working to give West access to the technologies they created next semester. Other projects include:

—Steereo, a Google Map-based iOS navigation app that stores favorite routes, plays sound in the direction the user is supposed to travel, and adjusts distances to number of steps. The distance-to-steps conversion idea came from West, says team member Leda Daehler. “Many visually impaired people count steps to measure distance, so we used the iPhone’s internal pedometer to put all the directions in terms of the user’s personal step size,” Daehler said. “Estimated times are also in terms of the user’s pace.”

—Several fun, tablet-based games that use only audio cues.

—A standard for putting RFID tags on objects so that they can announce themselves to a blind person’s smartphone as they move through a building. This project will continue in Winter 2017.

—A series of online coding lessons for people who are visually impaired. West had expressed interest in learning programming. “We looked into whether there were any coding tutorials for the visually impaired and there weren’t,” said student Gabriel Pascualy. “Programming’s a very visual thing and translating it into the context of not being able to see was difficult.”

India West discusses a project that is designed to teach coding to blind students with a computer science and engineering student Gabriel Pascualy who helped create it.  (Source: University of Michigan)

India West discusses a project that is designed to teach coding to blind students with a computer science and engineering student Gabriel Pascualy who helped create it.
(Source: University of Michigan)

West could see her future in programming—specifically in software development for the visually impaired. She’s taken a short course and volunteered to test apps for accessibility. Her work with this software engineering class may have bridged the gap in a more indirect way too.

“Working with these customers with different abilities gives students a completely different perspective on how to develop software,” Chesney said in a statement. “There’s this computer science myth that we build this thing and then we wait in our garage and somebody shows up to buy this thing and lavish money on us. But the reality is working with a customer, someone who looks at the project and says these are the things I like and these are the things I don’t, is absolutely invaluable to a computer scientist, particularly when their usage patterns are completely different than the developers.’”

Next year will be West’s last as a high school student. She plans to continue collaborating with Michigan Engineering, working with the students who developed the standard for putting RFID tags on objects. Through the Multidisciplinary Design Program, they’ll turn the Bob and Betty Beyster building into a “smart building,” where objects identify themselves as West moves through.

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