Science Square

  • Issue 83 / September - October 2011



    Epidermal electronics

    The Fountain

    1- Epidermal electronics
    Original Article: Kim, D-H et al., Science 333, 838 (2011). We often see patients in hospitals with many cables attached to their bodies. Now there is hope to replace these mobility-limiting settings with something very portable. Engineers have developed an ultrathin, stretchy, and flexible synthetic skin that consists of electronic components such as sensors, antennae, and light-emitting diodes (LEDs). Embedded solar cells or wireless power transfer can be employed to power the patch. The device is thin enough to stick to skin using only the short-range van der Waals forces without the addition of any adhesives, and it can be applied and removed like a temporary tattoo. As a result, electronic skin is much more comfortable than traditional electrodes and gives the user complete freedom of movement. These devices have many potential applications in medical diagnostics, including EEG and EMG sensors to monitor nerve and muscle activity. Gathering patient data during normal activity is especially beneficial for continuous monitoring of health and wellness. During the tests, the patches collected data accurately for up to six hours, and showed no signs of degradation or irritation to the arm, neck, forehead, cheek, or chin after 24 hours. In addition, the researchers used electronic skin to control a video game by collecting electrical activity of muscles from the user's throat, demonstrating the potential for human-computer interfacing. In the near future, patients with muscular or neurological disorders could use this technology to communicate with computers. There is one major obstacle for long-term use. The patch falls off after a few days due to the continual shedding of skin cells. Researchers are looking for ways around this so they can be worn for months at a time.

    2- Searching memory engines
    Original Article: Sparrow, B. et al., Science 333, 776 (2011). What is the capital of Liberia? Which year did Edison invent the light bulb? Are your fingers itching to "Google" the answers? Evidently, the answer is yes. Researchers led by Betsy Sparrow of Columbia University cleverly designed four experiments to investigate how we process information in our memory. In one experiment, participants were presented with trivia-like statements, e.g. "An ostrich's eye is bigger than its brain," to which they immediately thought about computers or accessing the Internet. In another experiment, participants were asked to type answers to trivia questions. The computer would either save or erase their answers. When participants thought their answers were saved, they remembered information less as opposed to the erased-from-the-computer-condition. In the other experiments, participants were given statements along with the names of the folders where one can reach that information (e.g. DATA, INFO, ITEMS). They remembered where to find the information (i.e. folders) more accurately than the information itself. To sum up, this research showed that we come to utilize computers or Google as external or transactive memory. In the 1980s, Daniel Wegner of Harvard University first coined the term "transactive memory." Dr. Wegner, co-author of this article, suggested that people relied on others such as spouses or friends to remember various things. However, it seems like the duty is all on Google now.

    3- Lasers come to life
    Original Article: Gather, M.C. & Yun, S.H., Nature Photonics 5, 406 (2011). Since its invention in 1960, the laser became an invaluable device that found uses in numerous applications in many segments of today's world, including science, medicine, industry, electronics, and entertainment. Laser, an acryonym for Light Amplification by Stimulated Emission of Radiation, works through a process where light amplifies by bouncing back and forth between two mirrors. Sandwiched between these mirrors, lasers utilize a gain medium made of non-biological materials such as dyes or crystal. Two physicists at Harvard Medical School, Seok Hyun Yun and Malte Gather, were able to replace gain medium with a living cell. The cells used in this study produce green fluorescent protein (GFP) the material that makes jellyfish fluoresce. When illuminated with relatively weak blue light, GFP amplified the light and the cell produced a visible green laser. Even though their biolaser is currently in the development stage, the researchers predict that it will be very useful in science and medicine in the future. For example, they suggest that biolasing may be used for unraveling the structure of living cells. Yun and Gather are now trying to integrate a nanoscale cavity inside the cell rather than using external mirrors. Such self-lasing cells may allow medical applications where cells can be specifically targeted for disease treatment.

    4- The smallest farmers of the world
    Original Articles: Brock, D. A. et al., Nature 469, 393 (2011). A social amoeba, Dictyostellum discoideum, lives independently and feeds on bacteria, but when the food becomes scarce, many amoebas bond and form a slug-like organism that can move around to find more resources to feed on. It was thought the amoeba exhausts all its resources by eating all nearby bacteria before forming the slug structure. Surprisingly, scientists from Rice University found that these single-cell organisms use a very simple form of agriculture in the form of bacterial husbandry. Agriculture in the general sense includes the scattering of food seeds, farming of crops, and harvesting. Humans have used agriculture for thousand of years and it was one of the transforming forces behind our switch from nomadic to settled lifestyles. Researchers showed that a group of amoeba, called farmers, eat less and engulf bacteria into their migratory systems instead of consuming all food they encounter. The slugs of the farmer amoeba travel slowly because of packed food, and one-third of Dicty found in nature turns out to be farmers. Apparently, being a farmer is a genetic trait but it comes with a cost: farmers produce less spores during feasts, but more during famine, which explains why there are both farmers and non-farmers still present. There are still many mysteries, yet this article shows the principles of frugality even in the single-cell realm.

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