posted on 2021-01-05, 08:43authored byHao Zhang, Qiao Yan, Joseph Horvat, Roger A. Lewis
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.