Figure shows the repeatability between three microneedles on a single chip. The plot presents the fluorescence from each needle in response to increasing concentrations of GFP. It is evident that for good coverage of pillars on the sensing area, all three microneedles from the same device react similarly inside the error range. Therefore, the microneedles arrays are highly reliable and produce an extremely While the preliminary concept and fluorescence measurements were conducted using GFP, subsequent measurements were done on real human serum samples for quantifying levels of the protein biomarker PSA in blood. Prostate-specific antigen (PSA), a protein biomarker originating from the prostate gland and found in the seminal fluid, has emerged as a pivotal component in the detection of prostate cancer.