Effect of metal ion type on the movement of hydrogel actuator based on catechol-metal ion coordination chemistry

- The type of ionoprinted metal ion can be used to tune the rate and extent of actuation for catechol-containing hydrogel.
- Metal ions that formed stronger interaction with catechol resulted in faster rate of actuation.
- Metal ions that form complexes with higher stoichiometric ratio with catechol resulted in higher extent of hydrogel actuation.
- Using different metal ions enabled different sections of the hydrogels to actuate at different rates, achieving sequential folding.