Dual-channel optical signal registration system for a liquid crystal gas sensor

Authors

DOI:

https://doi.org/10.31649/1681-7893-2026-51-1-339-346

Keywords:

liquid crystal; liquid-crystal sensing element; two-channel optical system; differential method; gas; test medium.

Abstract

The design principle of a dual-channel optical signal registration system for a liquid crystal gas sensor with spectral channel separation is presented. The architecture of the proposed system is based on the spatial and spectral decomposition of the optical signal into two independent channels, enabling the simultaneous acquisition of the measurement and reference signals from a single liquid crystal sensing element without mechanical switching or additional optical components.

The measurement channel (500–600 nm) records variations in the selective reflection band of the liquid crystal sensing element induced by interaction with the analyte gas environment. The spectral shift and intensity variation of the reflection band constitute the primary informative parameter of the sensor response. The reference channel (800 nm) operates outside the selective reflection band and provides effective compensation for illumination source instability, as well as external optical interference and ambient illumination fluctuations.

The differential signal normalization method is employed to eliminate the multiplicative component of source instability. This approach improves the signal-to-noise ratio by a factor of 7–13 relative to a single-channel configuration, substantially enhancing the overall measurement reliability, long-term stability, and reproducibility of sensor readings under varying environmental conditions.

A mathematical model of the dual-channel system has been developed, accounting for the spectral characteristics of the liquid crystal cell, the photodetector responsivity, and the noise contributions of each individual channel. Numerical simulation was performed to validate the proposed model and to optimize the key system parameters.

The principal metrological characteristics were determined as follows: operating range 0–80 ppm, limit of detection LOD ≈ 3,2 ppm at photodetector noise level σₙ ≤ 0,5%, relative measurement error ≤ 2.5%. The obtained results confirm the effectiveness of the dual-channel approach for enhancing the sensitivity, selectivity, and operational stability of liquid crystal-based optical gas sensors.

Author Biographies

I.P. Kremer, Lviv Polytechnic National University

Кандидат технічних наук, доцент, заступник директора з науково-педагогічної роботи

O.Yo. Shymchyshyn, Lviv Polytechnic National University

Кандидат технічних наук, доцент, доцент кафедри електронної інженерії

M.S. Ivakh, Lviv Polytechnic National University

Кандидат техних наук, доцент, доцент кафедри електронної інженерії

References

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Kukharchuk, V.V., Pavlov, S.V., Holodiuk, V.S., et al. Information conversion in measuring channels with optoelectronic sensors, Sensors , 2022, 22(1), 271

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Published

2026-06-17

How to Cite

[1]
I. Kremer, O. Shymchyshyn, and M. Ivakh, “Dual-channel optical signal registration system for a liquid crystal gas sensor”, Опт-ел. інф-енерг. техн., vol. 51, no. 1, pp. 339–346, Jun. 2026.

Issue

Vol. 51 No. 1 (2026)

Section

Optical And Optical-Electronic Sensors And Converters In Control And Environmental Monitoring Systems

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