Sensors Mag

January R&D Round Up

January 15, 2010 By: Melanie Martella, Sensors

E-mail Melanie Martella

Welcome to 2010 which will be, I hope, an improvement over 2009! This month's collection of interesting research results includes glitter-sized solar cells, an optical magnetic field sensor, and detecting plastic anti-personnel mines by measuring 3D temperature gradients.

A Dusting of Solar Cells
Continuing the miniaturization trend, researchers from Sandia National Laboratories have manufactured tiny photovoltaic cells that are significantly thinner than traditional 6 in. cells but manage to convert light to voltage at approximately the same efficiency. The MEMS-based devices are made of crystalline silicon, and are from 14–20 µm thick. The small size of the microcells means that even a small amount of silicon can be used to form well-controlled and efficient solar cells. As researcher Murat Okandan says in the news release about the research, "So they use 100 times less silicon to generate the same amount of electricity." The glitter-sized solar cells can be made using any size of commercially available wafer; even if one cell is defective the rest of the cells on the wafer can be harvested. To really get the full glory of this research, make sure to follow the link to the full press release. It's enough to make a jaded techie like myself perk right up.

Testing an Optical Magnetic Field Sensor
When it comes to measuring the tiny magnetic fields produced in the brain, heart, or elsewhere in the body, SQUIDs (superconducting quantum interference devices) are the instrument of choice. However, these devices work best when they're cooled down to -269°C and they need to be shielded from extraneous magnetic fields, which is complicated. However, thanks to work at NIST, an alternative may be on the horizon. NIST researchers have developed an optical magnetometer (PDF) that doesn't require such extreme cooling measures and is a mere 1 cm3 in size. In partnership with the German research institution Physikalisch-Technische Bundesanstalt, NIST measured the magnetic field of a human heart and relaxation curves of magnetic nanoparticles in PTB's magnetically-shielded room, comparing the measurements obtained using the optical magnetometer to those obtained using SQUIDs. The optical magnetometer proved capable of making measurements in the picotesla range. Work is now ongoing to develop a multichannel system.

Spotting Land Mines with Temperature
Anti-personnel mines are, quite simply, a blight. And detecting them—since most of them are now made of plastic with few metal parts—is difficult and dangerous, since metal detectors can't reliably find the things. According to an article in Science Daily, however, a new technique uses the temperature difference between the ground and the mine to aid in their detection. The research, conducted at the Fundación Española para la Ciencia y la Tecnología (FECYT), the Spanish Foundation for Science and Technology, relies on a nondestructive evaluation technique to generates 3D thermal maps of the ground. A specially programmed FPGA is used to measure thermal variations at the computational level, and its software is optimized to greatly reduce the number of calculations required, resulting in much faster results. Here's hoping that one of these techniques turns out to be foolproof so we can de-mine more quickly and effectively.

About the Author: Melanie Martella

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