Advances in SPR-Based Fiber Optic Sensors for Voltage/Electric Field Measurement—A Review

The article analyses and compares the characteristics of single and multilayer voltage-dependent fiber optic surface plasmon resonance (SPR) sensors in their most recent modifications and recommends future improvements. The recent invention in fiber optic SPR for voltage and electric fields has involved numerous applications in the different fields of biological, chemical, environmental, industrial, and many others. The theoretical and experimental investigations are examined in this review for the impact of voltage applied externally on the sensing module, the SPR curve’s shape, and resonance position. It has been found that depending on the resonance position shift on applied voltage polarity, the shape of the SPR curve is still the same under low voltage excitations. It utilizes a gold–silver bimetallic adaptation strategy to enhance chemical stability and voltage sensitivity. To raise the sensor’s sensitivity, the depth of the gold–silver metallic surface and the position of the specific wavelength for tracking have been examined.