A Novel Smart Hydrogel Strain Sensor for Efficient and Quantitative Detection of Blood Potassium Concentration with a Drop of Serum

Abstract Quantitative detection of potassium ion (K + ) concentration in serum is of great significance for clinical diagnosis and management. Although various methods are developed for quantitative detection of serum K + concentration, the existed techniques often fall short in the realization of rapid detection with small volume of serum sample. Here, a novel smart hydrogel strain sensor that combines poly( N ‐isopropylacrylamide‐ co ‐benzo‐15‐crown‐5‐acrylamide) (PNB) hydrogel and resistance strain gauge is developed for efficient and quantitative detection of serum K + concentration by converting and amplifying biochemical signals into easily measurable strain variations. By rationally regulating PNB hydrogels crosslinked with Laponite XLG nanosheets, the detection of serum K + concentration with PNB hydrogel strain sensors can be rapidly achieved with 2 min. Because the strain sensors with sensitive transformation enables the measurement of extremely slight deformation of hydrogels, only one drop of 16 µL serum is required to achieve efficient and quantitative detection of blood K + concentration with PNB hydrogel strain sensors. The PNB hydrogel strain sensors exhibit exceptional interference resistance and repeated detection performances. The proposed strategy not only offers a novel method for efficient and quantitative detection of blood K + concentrations, but also opens up a new window for developing novel detection methods for various applications.