MoS2 based ultra-low-cost, flexible, non-enzymatic and non-invasive electrochemical sensor for highly selective detection of Uric acid in human urine samples

While all reports on electrochemical uric acid (UA) sensors are on rigid electrodes and based on either complex fabrication procedures or multiple steps based synthesis techniques, this paper is the first demonstration of a single step hydrothermally grown MoS2 on aluminium foil (Al) based flexible electrochemical sensor for nonenzymatic detection of UA. FESEM images revealed MoS2 micro-flower like structure comprising of interlaced nanosheets while chemical characterization data confirmed the successful growth of few layered (> 4 layers) MoS2 on Al foil. The as-fabricated flexible sensor exhibited a limit of detection of 1.169 mu M, a response time of < 3 s, excellent reproducibility, selectivity towards UA over glucose, ascorbic acid and urea with a sensitivity of 98.3 +/- 1 nA mu M-1 (R-2 = 0.999) in the dynamic range of 10-400 mu M. This enhanced sensing ability can be attributed to high surface area of MoS2, more numbers of active sites resulting from large numbers of defects and edges and higher proportion of metallic 1 T phase than semiconducting 2H phase. The proposed sensor was also successfully evaluated for the detection of UA in a non-invasive sample like human urine and the data corroborates well with the UA concentration obtained from conventional biochemical tests performed in clinical laboratory. This highly sensitive, ultra-low-cost MoS2 based flexible electrochemical sensor paves way for the development of affordable lab on chip devices for a wide range of bioanalytical applications.