Chemoresistive and photonic hydrogel sensors of transition metal ions via Hofmeister series principles
By Price, Capri; Carroll, James; Clare, Tami L.
Published in Sensors and Actuators B: Chemical
2018
Abstract
We evaluate the sensory response of hydrogels composed of polyacrylic acid (PAA) co-polymerized with acrylamido-methyl propane sulfonic acid (AMPS) exposed to eleven different transition metal ions, which were reacted with hexacyanoferrate ions. Trends in the chemoresistive responses of the gels to ions of Cu2+, Fe2+, Mn2+, Ni2+, Pb2+, Co2+, Sn2+, Cd2+, Zn2+, Mo5+, and Ag+ due to the formation of metal hexacyanoferrate complexes are shown to depend upon the strength of the gel headgroup-ion interactions based on the Hofmeister series and confirmed using Raman spectroscopy. These hydrogels either showed a decrease in resistivity and swelling with increasing ion concentration or the opposite effect. Sensitivity by colorimetric and conductivity measurements was approximately 100 ppb, which can be adjusted by the gel