The Effects of Small Molecule Acids on PAAMPSA/PANI Systems

As biological sensing and monitoring increase in popularity, it becomes evident

that a sensitive, flexible, comfortable, and biologically compatible material is required to

make an optimal biosensor. As a result, polymeric piezoresistive sensors show great

promise in movement monitoring and biosensing. Their polymer composition provides

flexibility and stretchability which allows for unique sensor applications where traditional

metallic sensors are too brittle and rigid. The polymer complex to be used as a strain

sensor is composed of a templating poly(2-acrylamido-2-methyl-1-propanesiulfonic

acid), polyaniline, and a small molecule p-type dopant, originally phytic acid. By substituting the

small molecule dopant for various other small molecule acids, the impacts the various

dopants have on the strain sensor’s conductivity, mechanical properties, and

piezoresistive sensitivity can be studied. Typically, small molecule dopants that increase

conductivity decrease stretchability and mechanical stability, which stems from more

acidic dopants being able to protonate and facilitate ion transport throughout the sensor.

On the opposite hand, functional groups with increased hydrogen bonding tend to

increase mechanical properties, as well as allow for autonomous self-healing. By

increasing our understanding of the impact these various dopants have on the

properties of the strain sensor, we can tailor the usage of these small molecule dopants

as we try to increase the sensitivity and conductivity of our sensor for usage in

biosensing and kinesiological monitoring applications.