To demonstrate the potential of this setup for monitoring levodopa blood levels in a potential patient, we tested our biosensor barcode in human blood serum. We incubated the SWCNTs with serum and added various concentrations of levodopa. In the first step, we tested the response in 20 % blood serum and screened the samples with a NIR spectrometer attached to the previously described microscope. We observed a shift in the response curve towards higher levodopa concentrations (Figure and Table ). In addition, a positive intensity change of around 4 % to 8 % was noted upon the addition of PBS, which reduces the overall serum concentration and results in an increased SWCNT intensity. This effect contrasts with the addition of more PBS to a PBS-buffered solution, which typically decreases the SWCNT intensity (Figure ). The maximum achievable intensity change at 100 µM was found to be in the range of 10 % to 25 %. Given that concentrations below 0.1 µM exhibited minimal directional effect, we focused our subsequent experiments on the range of 0.1 µM to 100 µM and selected four different sensors for a barcode (PEG-PL-, C30-, (GT)10-& (GA)15-SWCNTs, Figure ). We repeated the experiment with the barcode reader and observed small but detectable response curves for this sensor barcode (Figure ). The maximum response at 100 µM was achieved by the C30-SWCNTs, yielding a 6 % response, while PEG-PL-SWCNTs exhibited a negative response of -2 %. To challenge the sensor barcode, we repeated the experiment using 100 % blood serum. The higher serum concentration resulted in decreased sensor responses to levodopa and showed a larger standard deviation among the samples (Figure ), but the qualitative trend was consistent.