High-tech coal mine canary.

High-tech coal mine canary One of coal mining's earliest systems for warning of the presence of methane gas, the canary in the coal mine, though low-tech, was extremely effective and rather easy to read: if the bird died, miners had to get out of the shaft. Today, the search for means to monitor for signs of danger continues. At an annual checkup, one could be given a whole battery of tests, each checking for the presence or absence of biological molecules that can be used to warn of potential health threats. These kinds of tests usually need not be done more than once a year, but for some health conditions, such as diabetes, daily monitoring by the patient or his or her caregiv-ers is required. In such cases, sensors need to work rapidly, be easy to use and relatively painless, and provide accurate results. Given the need for such monitoring, sensor technology development has been of keen interest to the medical community for several decades. For blood-glucose monitoring, recent technologies that show a great deal of promise include the use of electrochemi-cal or optical means to detect glucose. At this stage, however, accuracy remains an issue for both. For optical measures, there are problems with chemicals that have properties similar to those of glucose and thus result in false positive signals. For electrochemical methods, the measurement is based on the electrochemical oxidation of hydrogen peroxide that is produced when glucose is enzymatically broken down. The oxidation or reduction of chemicals other than hydrogen peroxide at the fixed electrode potential of this sensor, however, can generate false readings. A third means for biochemical detection uses a magnetoelastic sensor system whereby a sensor is coated with a pH-responsive polymer, which swells or shrinks depending on the surrounding pH. In response to a magnetic field, this coated sensor produces vibrations at a frequency related to the size of the sensor. Craig Grimes and colleagues at Pennsylvania State University have now applied this technology to detecting glucose levels and have developed a wireless, remote means to assess glucose concentration in solution (1). Two key features of this sensor are its inexpensive nature and its ease of production. Grimes told the JCI, " The sensor material — you can buy it on a reel, like tape-recording media, and it literally costs about $250 a kilometer. " The sensor is coated with the pH-sensitive polymer followed …