Magnetite-Based Resistor for Nitric Oxide Detection

The study demonstrates the fabrication of magnetite (Fe
₃
O
₄
) microspheres (MS) based magneto resistor (MR), for the detection of as low as 10 parts per billion (ppb) nitric oxide (NO) at room temperature. The Fe
₃
O
₄
MS with a diameter of nearly 430 nm, have been synthesized by a solvothermal method. The MR based gas sensor shows excellent sensitivity, fast response, and high recovery to NO at room temperature. Moreover after the interaction with NO, Fe
₃
O
₄
MS show an enhanced magnetic moment due to the increase in spin value from Fe
²⁺
(s = 2) to Fe
³⁺
(s = 5/2). MR sensor exhibits a limit of detection of 1.69 ppb with the highest sensitivity of 14.43% for the detection of 500 ppb of NO, with a response time of 10 to 20 seconds. The work aims to develop a proof-of-concept for the detection of NO using a simple method, and more effort would be needed to refine the device for a biological application.