Chu, A.; Schlecker, B.; Handwerker, J.; Künstner, S.; Ortmanns, M.; Lips, K.; Anders, J.: VCO-based ESR-on-a-chip as a tool for low-cost, high-sensitivity food quality control. In: 2017 IEEE Sensors : October 29-November 1, 2017, Glasgow, Scotland, UK, Scottish Event Campus (SEC) : 2017 conference proceedingsIEEE, 2018. - ISBN 978-1-5090-1012-7, p. 1
10.1109/ICSENS.2017.8233896
Open Access Version (externer Anbieter)
Abstract:
In this paper, we present a new VCO-based sensing method for electron spin resonance (ESR) spectroscopy, which greatly simplifies the experimental setup compared to conventional detection schemes. In contrast to previously presented oscillator-based ESR detectors, where the ESR signal was encoded in the oscillation frequency, in the new method, the ESR signal is sensed as a change of the oscillation amplitude of the VCO. Therefore, using a VCO architecture with a built-in amplitude demodulation scheme, the experimental setup reduces to a single permanent magnet in combination with a few inexpensive electronic components. Together with the new sensing principle, we present a theoretical analysis of the achievable limit of detection, which uses a perturbation theory based VCO-modeling for the signal and applies a stochastic averaging approach to obtain closed-form expression for the noise floor. Additionally, the paper also introduces a numerical model suitable for simulating oscillator-based ESR experiments in a conventional circuit simulator environment. This model can e.g. be used to optimize sensor performance early on in the design phase. Finally, all presented models are verified against measured results from a prototype VCO operating at 14 GHz inside a 0.5 T magnetic field.