Enabling the aqueous solution sensing of skin-conformable organic field-effect transistor using an amphiphilic molecule

Abstract Research on aqueous solution sensor has immense demand in biological sensing applications. While traditional organic field-effect transistors (OFETs) have shown promising prospect in the field of sensing, their application in the aqueous solution sensing far lag behind since the aqueous environment strongly limits the organic materials to work. Here, we design, somewhat counterintuitively, an approach to increase the affinity of OFET to aqueous solution by adding amphiphilic molecule in the hydrophobic semiconductor. This method enables the aqueous solution sensing of the OFET through providing a good wettability between the OFET and the aqueous environment. Benefiting from this, the OFET can detect glucose aqueous solution in the human blood range (0.5–2 mg/mL) and the strongest response derived from the variation of mobility is as high as 5600% when applied 1 mg/mL glucose solution. Under a curvature radius of 7.5 mm, the OFET still maintains the sensitivity to glucose down to 0.5 mg/mL. The sensing performance is tunable through changing the amphiphilic molecule with different Hydrophile-Lipophile Balance value and introducing dielectric material in semiconductor. In addition, the selective detection to aqueous solutions of glucose, raffinose, starch, and lactic acid is realized. Portable real-time detection is achieved by integrating the OFET with wireless transmission and a smartphone. When the glucose concentration exceeds the limit, a red-light signal can be triggered as a warning. The work develops a simple approach for OFET to achieve aqueous solution detection.