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The critical sensor: a new type of evanescent wave immunosensor
E F Schipper1, R P Kooyman, A Borreman
1MESA Research Institute, Department of Applied Physics, University of Twente, AE Enschede, The Netherlands.
Insights
A novel planar waveguide immunosensor was developed, offering a sensitive method for detecting adlayer growth. This critical sensor achieves high sensitivity comparable to existing technologies but with simpler fabrication and no metal layer requirement.
Area of Science:
- Optoelectronics
- Biosensing
- Surface Chemistry
Background:
- Surface adsorption changes refractive index, a phenomenon utilized in optical sensors.
- Existing sensors like surface plasmon resonance (SPR) and grating couplers have limitations in fabrication or material requirements.
Purpose of the Study:
- To develop a new planar waveguide immunosensor based on critical angle shifts.
- To evaluate the sensor's sensitivity and compare it with established technologies.
- To highlight the advantages of the new sensor regarding fabrication and material usage.
Main Methods:
- Development of a planar waveguide structure for sensing.
- Utilizing the principle of critical angle shift due to refractive index changes upon analyte adsorption.
- Experimental validation of the sensor's performance through immunosensing experiments.
Main Results:
- The sensor measures changes in refractive index contrast caused by surface adsorption.
- A lower detection limit of 2 x 10(-2) nm in adlayer growth (12 pg/mm2 analyte coverage) was achieved.
- Sensitivity is comparable to surface plasmon resonance and grating coupler sensors.
Conclusions:
- The developed planar waveguide immunosensor is a viable alternative for sensitive analyte detection.
- The sensor offers advantages in ease of fabrication, adjustment, and does not require a metal layer.
- This technology presents a promising platform for various immunosensing applications.
Abstract:
A new planar waveguide immunosensor has been developed in which adsorption at a surface, changing the refractive index contrast, is measured. In this "critical" sensor the change in the effective refractive index contrast is transducted to a shift of the critical reflection angle. The sensor's theoretically. In addition, an experimental sensitivity evaluation on the basis of several immunosensing experiments is presented. The obtained lower detection limit is 2 x 10(-2) nm in adlayer growth, equivalent to 12 pg/mm2 of analyte coverage. This sensitivity is comparable to the performance of the surface plasmon resonance sensors or the grating coupler sensors. However, the "critical" sensor has some advantages. These are mainly the ease of fabrication and adjustment prior to a measurement, and the fact that for an experiment no metal layer has to be used.