Highly sensitive, fast and wide dynamic range lactate sensor containing solvatochromic sensing membrane by combining the capacitance-to-phase conversion technique

We design and develop a low-cost, highly-sensitive, wide dynamic range interdigitated capacitor (IDC) lactate sensor based on the capacitance variation principle. We use Nile red, which has solvatochromic properties and this dye containing sensing membrane deposit into the interdigitated electrode (IDE) to prepare an IDC lactate sensing element. We apply the capacitance-to-phase conversion technique to detect lactate concentrations between 100 nM and 1 M by altering the dielectric constant of the membrane. As a result, the capacitance of the IDC sensing element change, introducing a phase shift and producing an output voltage. The sensitivity of the IDC sensing element is 11.28 ns/decade and offer a linear sensing response over a wide dynamic range with a correlation coefficient of R 2 ≈ 0.998. The IDC sensing element also offers an extremely stable response with a fast response time of 1.02 s and fast recovery time of 1.3 s. The relative standard deviation of the stability is 0.024. The proposed IDC lactate sensing element show/exhibit an excellent sensing performance compare to the other lactate-sensors.