Biocompatible micro, soft bellow actuator rapidly manufactured using 3D-printed soluble mold

Abstract

A micro, soft bellow actuator, which is fabricated using a biocompatible material (polydimethylsiloxane (PDMS)) and operates in a pneumatic manner that is harmless to the living body, has been experimentally validated using 3D-printed soluble molds and supports. Typical planar microfabrication techniques for flexible pneumatic actuators with complex geometries generally have inherent design limitations owing to the manner in which 2D thin films are stacked and require multiple lithographic and alignment steps. In this study, micro bellow actuators with 3D structures that cannot be fabricated using the existing softlithography techniques were designed by simulating the mechanical behavior of the actuator based on the nonlinear elastic properties of PDMS. The subsequently designed 3D-printed soluble-mold technique was used to fabricate the bellow actuators with a 10 mu m resolution, while taking into consideration the printing quality, which depends on the printing direction and layer thickness of the 3D printer. On evaluating the operating performance, the micro bellow actuator showed a displacement of 1540 mu m at the applied pneumatic pressure of 60 kPa and can apply a force of 0.14 N. Even after 10 000 repetitive operations, the change in the operating characteristic was less than 0.44%. It was also demonstrated that fast prototyping of actuators within 48 h is possible without any process revision, even with variable design changes or other soft polymer materials. The reported fabrication technique is a superior approach for fabricating 3D, sealed, soft pneumatic actuators for micro, soft robot applications.