Disposable Off-Chip Micro-Dispenser for Accurate Droplet Transportation

Abstract

Liquid dispensing in small scale is typically done by using either automatic syringe pumps or manual operation with syringes or pipettes. The micro-dispensers, which can precisely transport a variety of droplet fluids in the $\mu \text{L}$ range, have received increasingly more attention in the area of lab-on-a-chip. In this paper, we present the design of a portable, efficient, accurate yet cost-effective micro-dispenser, which is ideal for improving simple laboratory applications. Our proposed design is comprised of the main frame and a disposable main tank for accommodating a bulk volume of sample fluid. The whole unit functions as an off-chip reservoir to transport the sample fluid to elsewhere through a passive valve. The height of the disposable main tank and the diameter of the passive valve are carefully designed upon the physical properties of the sample fluid. Moreover, our micro-dispenser is equipped with a flexible layer of elastic diaphragm. An electromagnetic actuator is utilized to produce push-pull force, while a Peltier thermoelectric device supported by a fuzzy logic controller is dedicated to controlling the temperature within the tank. The experimental measurements of our prototyped device exhibit that our proposed design features multiple advantages over the conventional methods, including repeatable dispensing, high accuracy, disposability, and controllable temperature.