University of Utah physicists have developed an inexpensive, highly-accurate magnetic field sensor for scientific and possibly consumer uses based on a “spintronic” organic thin-film semiconductor that basically is “plastic paint.”

The new kind of magnetic-resonance magnetometer also resists heat and degradation, works at room temperature and never needs to be calibrated, physicists Christoph Boehme, Will Baker, and colleagues report online in Nature Communications.

An inexpensive and highly accurate “spintronic” magnetic field sensor developed at the University of Utah is shown here. The entire device, on a printed circuit board, measures about 0.8 inches by 1.2 inches. But the part that actually detects magnetic fields is the reddish-orange thin-film semiconductor, essentially “plastic paint," near the center-right of the device. Photo Credit: Christoph Boehme, University of Utah.

The magnetic-sensing thin film is an organic semiconductor polymer named MEH-PPV. Boehme says it really is nothing more than an orange-colored “electrically conducting, magnetic field-sensing plastic paint that is dirt cheap. We measure magnetic fields highly accurately with a drop of plastic paint, which costs just as little as drop of regular paint.”

The orange spot is only about 5-by-5 millimeters (about one-fifth inch on a side), and the part that actually detects magnetic fields is only 1-by-1 millimeters. This organic semiconductor paint is deposited on a thin glass substrate which then is mounted onto a circuit board with that measures about 20-by-30 millimeters (about 0.8 by 1.2 inches).

The new magnetic field sensor is the first major result to come out of the new Materials Research Science and Engineering Center launched by the University of Utah last September: a six-year, $21.5 million program funded by the National Science Foundation, the Utah Science Technology and Research initiative and the university.