On the performance quantification of resonant refractive index sensors

On the performance quantification of resonant refractive index sensors

2008 January 21; 16(2): 1020–1028 | Ian M. White and Xudong Fan
The paper discusses the performance quantification of resonant refractive index (RI) sensors, which are widely used for various applications due to their simplicity, low cost, and high throughput. The authors propose a rigorous definition for the detection limit (DL) of these sensors, which accounts for both the sensitivity (S) and the sensor resolution (R). The DL is defined as the ratio of R to S, and it characterizes the smallest detectable change in RI or the minimum amount of analyte that can be accurately quantified. The sensitivity (S) is the magnitude of the spectral shift of the resonant wavelength relative to the change in RI, while the sensor resolution (R) is the smallest possible spectral shift that can be accurately measured. The resolution is influenced by factors such as spectral resolution and system noise, including amplitude noise and spectral variations. The paper also explores the impact of various parameters on the detection limit, such as the fraction of the optical mode interacting with the sample (η), the Q-factor of the resonant mode, and temperature-induced spectral fluctuations. It highlights that high-Q-factor sensors are limited by temperature stabilization, while low-Q-factor sensors are limited by amplitude noise and spectral resolution. For biomolecule detection, the paper provides a method to convert the bulk RI sensitivity into a sensitivity for biomolecules, which is crucial for detecting low-density molecules on the sensor surface. The detection limit for biomolecules is calculated in a similar manner to the bulk RI analysis, providing a standardized tool for comparing different RI sensors. Overall, the proposed methodology aims to standardize the comparison of optical RI sensors and to guide the design of sensors with improved performance.The paper discusses the performance quantification of resonant refractive index (RI) sensors, which are widely used for various applications due to their simplicity, low cost, and high throughput. The authors propose a rigorous definition for the detection limit (DL) of these sensors, which accounts for both the sensitivity (S) and the sensor resolution (R). The DL is defined as the ratio of R to S, and it characterizes the smallest detectable change in RI or the minimum amount of analyte that can be accurately quantified. The sensitivity (S) is the magnitude of the spectral shift of the resonant wavelength relative to the change in RI, while the sensor resolution (R) is the smallest possible spectral shift that can be accurately measured. The resolution is influenced by factors such as spectral resolution and system noise, including amplitude noise and spectral variations. The paper also explores the impact of various parameters on the detection limit, such as the fraction of the optical mode interacting with the sample (η), the Q-factor of the resonant mode, and temperature-induced spectral fluctuations. It highlights that high-Q-factor sensors are limited by temperature stabilization, while low-Q-factor sensors are limited by amplitude noise and spectral resolution. For biomolecule detection, the paper provides a method to convert the bulk RI sensitivity into a sensitivity for biomolecules, which is crucial for detecting low-density molecules on the sensor surface. The detection limit for biomolecules is calculated in a similar manner to the bulk RI analysis, providing a standardized tool for comparing different RI sensors. Overall, the proposed methodology aims to standardize the comparison of optical RI sensors and to guide the design of sensors with improved performance.
Reach us at info@study.space