Design and implementation of combined liquid pump and active–passive mixer for a drug delivery system utilizing two 1-DOF piezoelectric actuated cantilever beams

Abstract

In a biomedical drug delivery system, liquid medication is provided to the patient through a saline solution, administered in tiny drops. The spread of the medicine in the solution is an essential aspect for the solution to become homogeneous. The present study introduces a combined pump and active–passive mixer arrangement consisting of dual piezoelectrically actuated 1-degree of freedom (DOF) Aluminium cantilever beams. The free end of each beam is attached to a borosilicate glass tube set-up that works as both pump and a mixer. The setup consists of two vertical tubes, connecting channels, a glass bulb, and a coiled tube. When the piezoelectric actuated cantilever beam is excited by an excitation voltage, it deflects and vibrates along with the glass tube arrangement resulting in the vertical tubes pumping liquid from the two separate glass containers due to the mechanical vibratory movement. The connecting channels pass the pumped fluid into the vibrating glass bulb and the coiled tube where these two liquids mix. We tested the mixing executions of four different geometries, G-1 – G-4, based on changed δ (coil curvature ratio), p (pitch), and n (number of windings). Initial pumping was started at 90 VP-P input voltage for all geometries, and the observed flow rate and velocity were 2.91 ml min−1 and 0.9160 mm min−1 for G-1 geometry. A UV–visible spectrophotometer was used to evaluate the mixing execution by measuring the solution's absorbance values before and after mixing.