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Tech Front: New Conductive Polymer Nanocomposites Hold Promise for Portable Devices

 

Researchers at Drexel University (Philadelphia) have developed a strong, flexible, electrically conductive nanocomposite material that could be used to power future wearable energy storage devices.

The conductive MXene-polymer nanocomposite material, created by researchers in Drexel’s Department of Materials Science and Engineering in collaboration with scientists at Dalian University of Technology in China, is very flexible yet has the strength to support many times its own weight. The researchers see potential for the material to improve electrical energy storage, water filtration and radio-frequency shielding in technologies ranging from portable electronics to coaxial cables.

Creating thin materials that can hold and disburse an electric charge while being contorted into a variety of shapes is a rarity in the field of materials science, the researchers noted. In addition, tensile strength, the strength of the material when it is stretched, and compressive strength—its ability to support weight—are valuable characteristics for these materials that are just a few atoms thick.
The flexible, conductive MXene-polymer nanocomposites created by Drexel University engineers could find uses in wearable energy storage devices.
“Take the electrode of the small lithium-ion battery that powers your watch, for example. Ideally the conductive material in that electrode would be very small—so you don’t have a bulky watch strapped to your wrist—and hold enough energy to run your watch for a long period of time,” said Michel Barsoum, Distinguished Professor in the College of Engineering. “But what if we wanted to make the watch’s wristband into the battery? Then we’d still want to use a conductive material that is very thin and can store energy, but it would also need to be flexible enough to bend around your wrist. As you can see, just by changing one physical property of the material—flexibility or tensile strength—we open a new world of possibilities.”

The flexible new material, called a conductive polymer nanocomposite, is the latest in ongoing research in Drexel’s Department of Materials Science and Engineering on a family of composite two-dimensional materials called MXenes. The development was the result of a collaboration between research groups of Yury Gogotsi, Distinguished University and Trustee Chair professor in the College of Engineering at Drexel, and Jieshan Qiu, vice dean for research of the School of Chemical Engineering at Dalian University of Technology in China. Zheng Ling, a doctoral student from Dalian, spent a year at Drexel, spearheading the research that led to the first MXene-polymer composites. The research at Drexel was funded by grants from the National Science Foundation (NSF) and the US Department of Energy.

“The uniqueness of MXenes comes from the fact that their surface is full of functional groups, such as hydroxyl, leading to a tight bonding between the MXene flakes and polymer molecules, while preserving the metallic conductivity of nanometer-thin carbide layers,” Gogotsi said. “This leads to a nanocomposite with a unique combination of properties.”

Drexel researchers have been examining MXenes for some time, and the engineers invented the layered carbide material in 2011. The team’s most recent work on MXenes was recently published in a paper, “Flexible and conductive MXene films and nanocomposites with high capacitance,” in the Proceedings of the National Academy of Sciences. The researchers reported that the material exhibits increased ability to store charge over the original MXene and 300-400% improvement in strength. To view an abstract of the paper, see http://tinyurl.com/olaah4g.  


Research for Collaborative Robots

As demand rises for collaborative robots that can work very closely with humans, more research is being allocated to scientists developing robots capable of handling tasks ranging from disaster recovery to health care and assembly-line work. The National Science Foundation, in partnership with the National Institutes of Health, US Department of Agriculture and NASA, on Nov. 19 announced $31.5 million in new awards to spur the development and use of co-robots—robots that work cooperatively with people.
The Baxter robot hands off a cable to a human collaborator—an example of a co-robot in action.
The awards are the third round of funding made through the National Robotics Initiative (NRI), a multi-agency program launched in September 2012 as part of the Advanced Manufacturing Partnership Initiative, with NSF as the lead federal agency.

“Robots and robotic systems have the potential to augment human abilities, improve our quality of life and perform dangerous tasks unsuitable for people,” said Suzi Iacono, acting assistant director of the Computer and Information Science and Engineering Directorate at NSF. “Working with our federal partners in NRI has spurred new research directions that weren’t previously possible without these collaborations.”

Ranging from $300,000 to $1.8 million over one to four years, these 52 new research awards advance fundamental understanding of robotic sensing, motion, computer vision, machine learning and human-computer interaction. The awards include efforts to develop soft robots that are safer for human interaction, determine how humans can lead teams of robots in recovery situations and design robots that can check aging infrastructure and map remote geographic areas. A full listing of the NRI investments made by NSF is available on NSF’s NRI Program page.


Optical Precision for Measurement and Inspection

“From the time that Eli Whitney first made the many parts of his gun interchangeable… we note an increase in the precision of measurements,” stated Lewis V. Judson, a physicist in the Office of Weights and Measures at the National Bureau of Standards (now NIST; Gaithersburg, MD) in SME Technical Paper TP60PUB1. “Measurement is the life line of progress.”

The fact that “a ray of light is an excellent straight line” (TP60PUB135) brought optical methods to popularity in place of mechanical measurements by surface tables, height gages, knee blocks or micrometers (TP63PUB40). TP60PUB135’s four articles from The Tool Engineer magazine include case studies on increasing the inspection rate of complex ammunition components by several hundred percent and optical trueing of large lathes in less than an hour.


Early Devices

Four unusual optical measuring instruments developed by Itek Corp., a former defense contractor, are described in TP67PUB150. A digital microinch measuring machine was developed to measure and guide the final polishing (figuring) of the irregular surface of nonspherical (aspheric) lenses. A ranging optical probe using modulated light focused to a minute spot was used in applications where an electronic probe stylus was unsuitable. An electronic eye device provided, in a limited manner, the visualization and correlation functions of the human eye and brain combination. Electronic image motion stabilization permitted stabilizing an image for photography in the presence of rapid relative angular motion between the object and camera.

Digitized data for an optimum milling strategy (K. Galanulis and J. Tyson, TP08PUB22).A portable instrument with lighting and optics developed at NASA’s George C. Marshall Space Flight Center (Huntsville, AL) aided product control of separable tube connections, where leaks can be life threatening and expensive. The flared tubes typically produced at Marshall relate to space vehicles, but tubing connections are an issue in many other applications in the military, aerospace, marine and machinery industries (TP67PUB153).

“Automatic inspection of manufactured materials is no longer a dream or ideal of cost conscious management, but is in fact a reality. It is also apparent that the human eye and brain is not as consistent or reliable as what we would like to see reflected in our final product quality,” stated the author of TP70PUB7. Several applications of electro-optical techniques for in-process inspection are described, including the unique capabilities of scanning electron microscopes, rotating mirrors and fiber optic bundles. Other papers detail automated optical inspection of small bore surfaces in an automotive brake system valve body (TP72PUB128), inspection and sorting of precision springs (TP79PUB125) and automatic optical inspection of printed circuit boards before solder (TP87PUB487).


Call It Machine Vision

Electro-optical sensing for part inspection was well established by the time the term “machine vision” was heavily publicized as a crucial contribution to robotics. As explained in TP82PUB185, most inspection applications require high-resolution sensors relative to existing gages or visual inspectors, while robot guidance for simple tasks needs considerably lower resolution.

A robust, flexible optical feature extractor system for machine vision high-speed inspection applications is summarized in TP87PUB167, and TP89PUB313 describes the application of machine vision in the form of three identical laser gaging systems in a flexible manufacturing cell.

Papers dealing with many techniques for inspection were presented at SME events such as Vision, Precision Metrology with CMMs, MicroManufacturing and North American Hydroforming. Topics include selection and application of noncontact optical probes on coordinate measuring machines (CMMs) in TP99PUB152, processing of micromold cavity flow images with a transparent mold and high-speed camera system (TP07PUB140) and digitizing and analyzing the dimensional, forming and material property aspects of metal sheet parts and tools (TP08PUB22). 

TechFront is edited by Senior Editors Patrick Waurzyniak, pwaurzyniak@sme.org, and Ellen Kehoe, ekehoe@sme.org.

 

This article was first published in the January 2015 edition of Manufacturing Engineering magazine. Click here for PDF.


Published Date : 1/1/2015

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