A mass-sensitive pH sensor based on a stimuli-responsive polymer

摘要

A pH sensor is described based on a reversible,mass-changing pH-responsive hydrogel.While the hydrogel can be usee with any mass based sensor,in this work it is coupled wiht a magnetoelastic sensor the resonance frequency of which corresponds with applied mass load.The poly(acrylic acid-co-isooctyl acrylate)haydrogel,with acrylic acid (80%)and N,N-methylenebis(acrylatmide)cross linker,was synthesized by free radical polymerization.lExcellent adhesion between the ribbon-like magnetoelastic sensor and the pH responsive hydrogel is cahieved by pre-coating the sensor with a layer of polyurethane,and adding 1-(3-dimethylaminokproppyl)_3ethylcarbodiimide (EDC0into the hydrogel solution.The pH sensor response is accurately fit using the equation f_r=49.891-1.04 pH +0.048 pH~2.The average change in sensor resonance frequency is 506 Hz/pH,approximately 1%/ph of the resonance frequency value,from pH 4.4 TO 8.5.Measurement resolution between pH 4.4 and 8.5 is 0.02 pH units,corresponding to a resonance frequency measurement error (standard deviation)of 2.9 Hz.