Tracking a silent killer: Comparison of grating and non-grating palladium-functionalized optical fiber SPR sensor for carbon monoxide detection

Abstract

Carbon monoxide (CO) is a leading cause of poisoning deaths globally. CO exposure can cause severe health effects, ranging from neurological and cardiovascular symptoms at low levels to loss of consciousness and death at high or prolonged levels. Hence accurate and early detection of CO is essential for public health and environmental safety. To detect CO gas, this paper presents the design and performance analysis of palladium-based fiber optic surface plasmon resonance sensor. Palladium (Pd) readily adsorbs CO molecules and enables sensitive and selective signal transduction in sensor systems, making it an efficient biorecognition layer for CO detection. The sensor’s response is analyzed using finite element method, with an emphasis on important performance metrics such as resonance shift and modal loss. Grating and non-grating Pd biorecognition layers are demonstrated to compare the performance of sensors. Introducing a Pd grating enhanced the sensor’s sensitivity by approximately 12.7 %, increasing from 6300 nm/RIU in the non-grating configuration to 7100 nm RIU⁻¹ with 100 nm residual cladding, 30 nm air gap width and 20 gratings. This research also provides a first-principle study of CO adsorption on Pd surface by density functional theory to examine the specific adsorption behavior of analyte, which remains a major challenge in the field. Two surface geometries, i.e., (1 × 1) and (2 × 1), were investigated; resulting in the (2 × 1) structure exhibiting more desirable adsorption character. High sensitivity and efficiency are demonstrated by the suggested biosensor in the detection of CO for the development of ultrasensitive SPR sensors.