| dc.description.abstract | pH sensors are widely used to monitor chemical reactions, environmental conditions, and physiological pH due to the importance of alkalinity/acidity in these applications. Currently, the most widely used techniques for measuring pH are glass electrodes and single use pH strips. However, both methods have their limitations (e.g. portability and fragility for glass electrodes, limited reuse and poor sensitivity of pH strips). Herein, we use layer-by-layer (LbL) electrostatic self-assembly to fabricate a flexible and highly sensitive titanium carbide (Tvi3Cv2Tvx) MXene based pH sensor. Tiv3Cv2Tvx is the most common MXene to date and has drawn considerable attention due to its high conductivity and functionalized surface. By combining Tiv3Cv2Tvx with a positively charged polymer via LbL assembly, we successfully fabricate nanometer scale thin films. As the sensor is exposed to environments of varying pH, the hydroxyl surface groups of the Tiv3Cv2Tvx (de)protonate as Hv3O^+ and OH^- ions interact with the surface. This leads to a change in electrostatic attraction between nanosheets and a reduction in the number of active sites. When this occurs, the resistance of the sensors changes, allowing for use of the materials as a resistive pH sensor. With the inclusion of a pH sensitive polymer, such as BPEI, we show the ability to enhance sensitivity of the sensor due to the conformational changes of BPEI due to (de)protonation with changes in pH. This work discusses the use of Tiv3Cv2Tvx in a highly sensitive flexible pH sensor and creates prospects in the field of wearable and portable sensors. | en |
