June R&D Round Up

E-mail Melanie Martella

I've got some very fun research stories for you this month. Specifically, a new tactile sensor that lets robots feel, plastic paint that doubles as a magnetic field sensor, and a clever paper diagnostic test for point-of-care applications.

A New Tactile Sensor
One of the areas of research in robotics is adding tactile sensing to robots to enable them to interact with their environment by sensing (and identifying) what they're touching. This is particularly important and desirable for advanced prosthetics because humans rely on tactile feedback for so many things. Professor of Biomedical Engineering Gerald Loeb and recently graduated doctoral student Jeremy Fishel, all from University of Southern California's Viterbi School of Engineering, have created a specially designed robot that can actually distinguish among a variety of common materials based on touch. The robot incorporates both the BioTac sensor, which mimics our flesh-and-bone fingertips and a new algorithm that imitates human strategies for investigating and exploring our surroundings. The sensor has a liquid filling covered by a soft, flexible skin (complete with fingertips to boost its sensitivity to vibration). As the sensor moves over a surface, the action causes vibrations in the finger that are detected by an internal hydrophone. The algorithm incorporates the movements we make when we use touch to explore a new object. For a much fuller discussion, links to the Frontiers in Neurorobotics article, and a nifty video, check out "Robots Get a Feel for the World at USC Viterbi."

It's Paint! It's a Magnetometer!
What's orange, cheap, and detects magnetic fields? The answer comes courtesy of University of Utah physicists Christoph Boehme, Will Baker, and their fellow researchers, who have developed a spintronic organic thin-film semiconductor called MEH-PPV that can detect a wide range of magnetic fields from the very weak to the very strong and can measure the strong ones as long as it can carry a current. As described in the article, "A 'Dirt Cheap' Magnetic Field Sensor from 'Plastic Paint'", a 1 by 1 mm area within a 5 by 5 mm drop of the conductive paint (which sits on a thin glass substrate atop a small PCB) can act as an accurate magnetometer. A current applied to the paint generates radio waves across it; changing the current changes the frequency of the radio waves. If a magnetic field is present and the frequency of those radio waves matches the magnetic field, then the spins of the paint's electrons and holes will flip, producing an electrical current from which magnetic field strength is determined. (I have to admit that I'm fascinated by these paint as sensor types of research because just think of how they could be used!)

A Paper-based Diagnostic Tool
While people are being terribly inventive when it comes to complicated medical diagnostic tools, there's also a need for fast, easy, diagnostic tools that can be used at the point of care, and that's where paper-based biosensors come in. The most recent one to come to my attention is the aptamer-based origami paper analytical device for electrochemical detection of adenosine developed by researchers from the University of Texas at Austin and the University of Illinois at Urbana-Champaign. What they've done is to take paper that wicks fluids particularly well, in this case chromatography paper, and then used wax printing to make parts of it hydrophobic, allowing them to create paper that will suck the sample in and wick it to where it needs to be. On one half of the paper they've printed a sample inlet that connects to two channels, each of which connects to a narrow chamber that containes the desired reagents (that are also printed on). On the other half of the paper, they silkscreen conductive carbon ink to form electrodes. That done, they fold the paper in half, connecting the reagent chambers to the electrodes, laminate the whole thing, and voila! A self-contained biosensor! Add the sample and if your desired chemical component is present, the biosensor will produce an electrical potential that can be measured using a voltmeter. In the case of the sensor described in the Phys.Org article "Rapid test uses origami technology", they're using the technology to measure adenosine, an important biochemical. I'm not sure how folding something in half counts as origami, but hey, it's a remarkably clever device regardless.

(If you haven't seen it, Between the Folds is a an excellent documentary about origami and its practitioners, and how they use paper folding for art, engineering, and education.)