Fig. 4: Ultrasensitive refractive index imaging sensor based on the ring stripe shift of the thickness-modulation chip through the dGMR.

a The structure of the sensing chip and the measured and calculated thickness profiles. In the three-dimensional coordinate system (x-y-t), a point represents the thickness of the dielectric layer at position (x-y), and the spatial distribution of the thickness is characterized by the surface fitted by the discrete points. The image in the x-y plane is a contour map of the fitted thickness spatial distribution. b The refractive index sensing results. (i) The measured distinct ring pattern images under different concentrations. (ii) The curve between the pixel shift and concentration, as well as the sensitivity curve. c The sensing resolution analysis. d The analysis of sensitivity and dynamic range as thickness gradient varies. e The new measurable cycle, which can widen the dynamic range of concentrations, from range (0, 1.0%) to additional range (1%, 2%), and so on, by using different incident angles in different measurement cycles. Dynamic range cycles can be continuously increased by simply re-adjusting the incident angle. f In the new dynamic range, the maximum experimental sensitivity can reach 990000 pixel/RIU (The resolution of the CMOS camera is 1608 × 1104 pixels). g The multi-channel sensing chip setup and the high-throughput imaging sensing with different solutions.