Abstract
In this paper, we present an in-depth analysis of a voltage-controlled oscillator (VCO)-based sensing method for electron spin resonance (ESR) spectroscopy, which greatly simplifies the experimental setup compared to conventional detection schemes. In contrast to our previous oscillator-based ESR detectors, where the ESR signal was encoded in the oscillation frequency, in the amplitude-sensitive method, the ESR signal is sensed as a change of the oscillation amplitude of the VCO. Therefore, using 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. We present a theoretical analysis of the achievable limit of detection, which uses perturbation-theory-based VCO modeling for the signal and applies a stochastic averaging approach to obtain a 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 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 inside a 0.5 magnetic field.
Highlights
Electron spin resonance (ESR) is a very powerful spectroscopic method which is used extensively in a large variety of disciplines including chemistry, material science and the life sciences (Twahir et al, 2015, 2016; Azarkh et al, 2013; Qi et al, 2014; Qin and Warncke, 2015; Fehr et al, 2011, 2012)
We present an in-depth analysis of a voltage-controlled oscillator (VCO)-based sensing method for electron spin resonance (ESR) spectroscopy, which greatly simplifies the experimental setup compared to conventional detection schemes
In contrast to our previous oscillator-based ESR detectors, where the ESR signal was encoded in the oscillation frequency, in the amplitude-sensitive method, the ESR signal is sensed as a change of the oscillation amplitude of the VCO
Summary
Electron spin resonance (ESR) is a very powerful spectroscopic method which is used extensively in a large variety of disciplines including chemistry, material science and the life sciences (Twahir et al, 2015, 2016; Azarkh et al, 2013; Qi et al, 2014; Qin and Warncke, 2015; Fehr et al, 2011, 2012). The oscillator-based detection concept was extended to the use of voltage-controlled oscillators (VCOs) by Handwerker et al (2016), which allows for a great simplification of the experimental setup, thereby, for the first time, enabling the design of battery-operated, portable ESR spectrometers Such portable ESR spectrometers can potentially have a very large impact on (emerging) disciplines such as the analysis of irradiated food (Chauhan et al, 2009), the study of wine oxidation (Elias et al, 2009), the prevention of the formation of free radicals in vegetable oils (Ottaviani et al, 2001), onsite radiation dosimetry (Romanyukha et al, 2014), pointof-care transcutaneous oxygen monitoring (Wolfson et al, 2014; Cristea et al, 2021) or measurements of skin antioxidant capability (Haag et al, 2011).
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
