The self-generated peristaltic motion of cascaded pneumatic actuators for micro pumps

This paper presents a new actuation mechanism for the self-generated peristaltic motion of cascaded actuators and its application to micro pumps. The operational method is based on the fluidic circuit of an elastic tube. The elastic tube is modeled as a ladder network consisting of fluidic resistances in series and fluidic capacitances in parallel like multi-stage low-pass filters in an electrical circuit. All segments of the lumped model of the elastic tube have different dynamic characteristics because their time constants are different. In other words, all segments should be deformed sequentially like peristaltic motion. This phenomenon has good potential to cause peristaltic motion of the cascaded actuators in response to the application of single-phase pneumatic signals. Analogues between the electrical and fluidic circuits were applied to a pneumatic micro pump with a micro fluidic channel and three pneumatic actuators connecting a unique micro channel for supplying the compressed air. The polymeric micro pumps were fabricated with soft lithography using only polyimethylsiloxsane. The proposed working principle was verified through simulation of the static deformation of the cascaded actuator diaphragms and the actuator, as well as tested experimentally. The dual operational modes of the proposed device (i.e., rubber-seal valve and peristaltic pumping mode) were also verified and successfully demonstrated in a liquid pumping test of the single and double pumps.