Piezoresistive and Electrical Properties of a Catecholic Amino Acid-Polyacrylamide Single-Walled Carbon Nanotube Hydrogel Hybrid Network

We have developed a functional hydrogel combining the advantages of single-walled carbon nanotube (SWCNT) hydrogels and 3,4-dihydroxy-L-phenylalanine (L-DOPA) that would be expected to lead to a material with elevated piezoresistive ability. SWCNT hydrogel precursors were thus embedded into the catecholic amino acid 3,4-dihydroxy-L-phenylalanine-polyacrylamide (L-DOPA-PAM) hydrogel to form a L-DOPA-PAM-SWCNT hydrogel hybrid network. This hybrid network as formed was soft but became a hard gel at room temperature. An advantage of this material design is the prevention of overoxidation of L-DOPA to maintain enough free catechol groups to endow the desired properties. Several characterization techniques, including optical microscopy, field-emission scanning electron microscopy, Raman spectroscopy, and dynamic mechanical analysis, were utilized to characterize the L-DOPA-PAM-SWCNT hydrogel hybrid network. The negative piezoresistive effect and electrical properties of the L-DOPA-PAM hydrogel and the L-DOPA-PAM-SWCNT hydrogel hybrid network were measured under different pressures and at different times after the application of pressure started, demonstrating the potential for pressure-sensing applications.

Automated summary

The study focused on developing a functional hydrogel with enhanced piezoresistive ability by combining SWCNT hydrogels and L-DOPA. The hybrid network showed potential for pressure-sensing applications and maintained enough free catechol groups to endow the desired properties. Various characterization techniques were utilized to study the L-DOPA-PAM-SWCNT hydrogel hybrid network.