Selective droplet sampling using a minimum number of horizontal pneumatic actuators in a high aspect ratio and highly flexible PDMS device

This paper presents a droplet sampling device driven by horizontal pneumatic actuators. A high aspect ratio and highly flexible PDMS (polydimethylsiloxane) structure was proposed for carrying out larger number of sampling than the number of actuators. Large deformation of the actuators caused domino-deformation of parallel walls, and the deformations allowed for selective collection of target droplets. The dimensions of the PDMS structure and the ratio of resin to curing agent were optimized for efficient sampling under the low pressure applied to the actuators. Five sampling modes were achieved in the simple one-layer structure consisting of one inlet, four walls, one drain channel, and two pneumatic actuators, formed by single-step soft lithography process.