Fast polymeric thermal expansion for dual-stage actuation in hard disk drives

Polymer, such as SU8, is more thermally expandable than silicon, and it has a potential to build a more powerful thermal actuator. Yet, it is limited to by slow response time to electro thermal activation. In this work, polymeric composite thermal unimorphs have been built by integrating silicon heat fins in the polymer at small spacing (10μm). With a small heat capacity in each polymeric spacer, fast polymeric thermal expansion is demonstrated at a time constant less than 1ms. This polymer composite micro-actuator was used to drive a femto slider for fast dual-stage micro-actuation in hard disk drives.