Polymer-integrated optical fiber Fabry–Pérot interferometer with Vernier effect for the detection of myoglobin

Acute myocardial infarction (AMI) is the most severe manifestation of coronary artery disease and one of the leading causes of morbidity and mortality worldwide. The concentration of myoglobin (Mb) in serum has been regarded as an essential indicator for the early diagnosis of AMI. Developing a rapid, sensitive, and accurate Mb detection method is very important for the early diagnosis of AMI. This study reports a fiber optic biosensor based on polymer and Vernier effect composite sensitization for real-time detection of serum Mb concentration. The sensor is made of a Fabry–Pérot interferometer cascade tapered microfiber filled with photothermal material polydimethylsiloxane. Two interference structures with similar but unequal free spectral range are combined, and the superposition spectrum produces periodic interference fringes, forming a fiber sensor with a Vernier effect. By detecting the photothermal signal generated by the absorption of light by Mb, marker-free, specific detection can be achieved. The sensing device attained a sensitivity of 5.235 nm/(mg/L) in the 0.0001–10 mg/L concentration range. The linearity reached 0.9978, with a limit of detection of 3.82 ng/ml, which meets the sensitivity requirements for detecting Mb concentration in serum, and the detection time was less than 40 s, which has potential in the early diagnosis of related diseases.