A method of assaying an analyte in a sample is disclosed. The method includes having a sample holder with a sample contact area for contacting a sample with an analyte, having a plurality of calibration structures on the sample contact area of the sample holder, imaging a part of the sample contact area that has the calibration structures, and using an algorithm that includes an image, calibration structures in the image, and artificial intelligence and/or machine learning to identify the analyte and/or determine the analyte concentration.