NMR on a Chip: a Micro-NMR Device for in situ Detection of Chloride in Concrete
The goal of this Engineering Microsystems: "XYZ" on a Chip project is to investigate the hypothesis that a micro nuclear magnetic resonance (NMR) based detector, defined as all aspects of an NMR other than the magnet and power supply, can detect chloride ion in concrete. The coils, oscillator, and essential electronics of an NMR, typically a large expensive device, are being created on a single chip with the CMOS process. The coil turns are one micron thick and one to two millimeters in diameter. The team includes faculty from civil engineering, chemical engineering, electrical engineering, and physics. The project's first stage is modeling and theoretical analysis of a micro NMR. The second stage consists of experiments aimed at demonstrating that the micro NMR can detect protons. This is a useful intermediate objective because the response of protons is 100 times larger than chloride and the signal can be used for calibration of the chloride detection. The third stage is measuring the concentration of free chloride in concrete. The results of this work underpin a sensor technology that could have a substantial impact on the nation's civil infrastructure. For example, an economical chloride sensor based on NMR and dispersed throughout a bridge deck can trigger remediation that prevents loss of the structure due to corrosion of the steel reinforcement. The broader impact of the project is creation of a technology that could find biomedical and other applications.