Robust Calibration Transfer in Noninvasive Ethanol Measurements, Part II: Modification of Instrument Measurements by Incorporation of Expert Knowledge (MIMIK)

Abstract

Several calibration transfer methods require measurement of a subset of the calibration samples on each future instrument, which is impractical in some applications. Another consideration is that these methods model inter-instrument spectral differences implicitly rather than explicitly. The present work argues that explicit knowledge of the origins of inter-instrument spectral distortions can benefit calibration transfer during the fabrication and assembly of instrumentation, the formation of the multivariate regression, and its subsequent transfer to future instruments. In Part I of this work, a Fourier transform near-infrared system designed to perform noninvasive ethanol measurements was discussed and equations describing the optical distortions caused by self-apodization, retroreflector misalignment, and off-axis detector field of view were provided and examined using laboratory measurements. The spectral distortions were shown to be nonlinear in the amplitude and wavenumber domains, and thus cannot be compensated by simple wavenumber calibration procedures or background correction. Part II presents a calibration transfer method that combines in vivo data with controlled amounts of optical distortions in order to develop a multivariate regression model that is robust to instrument variation. Evaluation of the method using clinical data showed improved measurement accuracy, outlier detection, and generalization to future instruments relative to simple background correction.

Evaluation of a new non-invasive measurement technique based on bioimpedance spectroscopy to estimate blood alcohol content: a pilot study

“…Transdermal alcohol sensors collect reliable data on alcohol consumption but lag behind breath alcohol levels by one or more hours [20]. Furthermore, spectroscopic techniques showed promising results due to an alternative blood and breath test [21][22][23]. However, until now, no procedure including bioimpedance for BAC estimation has entered the clinical routine, although BAC estimation by bioimpedance measurements is a non-invasive, cheap and easy approach.…”

Review of Ethanol Intoxication Sensing Technologies and Techniques

“…The authors also considered the difference in probe design as an attributing factor to the difference between sites of measurement. The research regarding the analytical side of the operation of these devices was conducted by TruTouch Technologies [100][101][102][103].…”

Robust Calibration Transfer in Noninvasive Ethanol Measurements, Part I: Mathematical Basis for Spectral Distortions in Fourier Transform Near-Infrared Spectroscopy (FT-NIR)

“…The resulting increase in spectral variance will have a detrimental impact that must be mitigated by the multivariate calibration and calibration transfer techniques that are being used. Part II 25 focuses on a method for incorporating controlled amounts of the spectral distortions into clinical calibration data and evaluating the impact of their inclusion, with and without background correction, on multivariate calibration transfer in noninvasive ethanol measurements.…”