Micropipette-Based Microfluidic Device for Monodisperse Microbubbles Generation.

Carlos Toshiyuki Matsumi,Walter Duarte Araújo Filho,Wilson José Da Silva,Joaquim Miguel Maia,Rigoberto E M Morales,Fábio Kurt Schneider

doi:10.3390/mi9080387

Abstract

Microbubbles have various applications including their use as carrier agents for localized delivery of genes and drugs and in medical diagnostic imagery. Various techniques are used for the production of monodisperse microbubbles including the Gyratory, the coaxial electro-hydrodynamic atomization (CEHDA), the sonication methods, and the use of microfluidic devices. Some of these techniques require safety procedures during the application of intense electric fields (e.g., CEHDA) or soft lithography equipment for the production of microfluidic devices. This study presents a hybrid manufacturing process using micropipettes and 3D printing for the construction of a T-Junction microfluidic device resulting in simple and low cost generation of monodisperse microbubbles. In this work, microbubbles with an average size of 16.6 to 57.7 μm and a polydispersity index (PDI) between 0.47% and 1.06% were generated. When the device is used at higher bubble production rate, the average diameter was 42.8 μm with increased PDI of 3.13%. In addition, a second-order polynomial characteristic curve useful to estimate micropipette internal diameter necessary to generate a desired microbubble size is presented and a linear relationship between the ratio of gaseous and liquid phases flows and the ratio of microbubble and micropipette diameters (i.e., Qg/Ql and Db/Dp) was found.

Highlights

IntroductionThere has been a growing interest in the application of microbubbles (i.e., as bubbles in the range of 1–1000 μm) in various fields of medicine, pharmacology, and chemistry, as well as in the food industry [1]
In recent years, there has been a growing interest in the application of microbubbles in various fields of medicine, pharmacology, and chemistry, as well as in the food industry [1]
We present the production of smaller microbubbles and a study on microbubble production linearity in relation to gaseous and liquid phase flow as well as an experimental-based estimation curve correlating the micropipette internal diameter as a function of the microbubble diameter considering a given emulsion and various gaseous and liquid phase flow values

Summary

Introduction

There has been a growing interest in the application of microbubbles (i.e., as bubbles in the range of 1–1000 μm) in various fields of medicine, pharmacology, and chemistry, as well as in the food industry [1]. An electric field is applied between the outer channel and a grounded collector base, with sufficient intensity to exceed the surface tension threshold of the liquid, forming a cone from the channel mouth from which a very fine jet emerges. In 2014, Parhizkar, Stride, and Edirisinghe have shown a microfluidic setup combined with electrohydrodynamic processing of bubble formation at different applied voltages and with different liquid properties. In their experiments they observed that the diameter of the bubble decreased dramatically with the increase of the voltage between 0 and 9 kV, for solutions with viscosity between 1.3 mPa·s and 36 mPa·s. Careful selection of operating conditions (i.e., speed of rotation and the working pressure of the solution) is vital to the success of the process due to the minimum pressure threshold and a minimum rotational velocity for bubble formation, below this threshold the bubbles are not formed due to insufficient fluid flow or low centrifugal velocity [11]

Methods

Results

Conclusion