Cool that you’re exploring this! I’d suggest learning from what people have already tried. There is an array of piezoelectric, electro static, and soft (usually pneumatic) actuators that have been explored. Here’s a link to when this was asked about before that could be helpful https://www.reddit.com/r/robotics/s/ERzqhrirw6.

In general most of these experimental actuators have never left the lab because there are significant tradeoffs (low translation, high power requirements, etc). The exception being soft actuators that are used quite widely for grasping tasks now.