SIMPLE analytical model for smart microfluidic chip design

Significance 

The flow control of pumping systems is an important aspect of microfluidic devices. Technically, it allows the integration of bioassays on-chip by accurately controlling the flow dynamics. Self-powered micropumps are available in different sizes to permit portability and use in different applications. In addition, surface tension-based platforms, in which the pumping process is supported by liquid wicking through capillary action, is widely preferred owing to its robustness, affordability, and portability.

Despite the advantages, self-powered channel-based systems are prone to low sensitivity and specificity of the analysis attributed to the interferences due to unsteady capillary effects. This requires hydrophilization of the channels to obtain the desired capillary effects, which is time-consuming and expensive. To this end, researchers have been looking for alternative solutions and have identified hybrid microfluidic devices, which is a combination of both channel-based and paper-based microfluidics, as a promising candidate.

Even though hybrid microfluidic devices have exhibited significant improvements, a few challenges including the need for hydrophilic channels and the difficulty to work with little volumes are yet to be resolved. However, the recent development of self-powered imbibing microfluidic pump by liquid encapsulation (SIMPLE) have addressed most of the aforementioned challenges. The system does permit any contact between the sample and the porous materials thus eliminating any possibility of interference. Alternatively, studies have also shown that the performances and flexibility of the microfluidics can be enhanced by effective chip design to allow adjustment of the flow control of pumping systems. This will ensure precise control of the flow dynamics, which are an important consideration in the development of point-of-care bioassays. Furthermore, several analytical models have been presented to describe the pumping dynamics in both paper- and channel-based microfluidics with little done for hybrid systems like SIMPLE. This includes taking into account the design parameters to optimize the chip design and obtain the desired flow rate.

Recently, researchers: Dr. Francesco Dal Dosso, Yura Bondarenko, Dr. Tadej Kokalj and led by Professor Jeroen Lammertyn at MeBioS-Biosensors Group of KU Leuven, investigated the pumping behavior of the hybrid SIMPLE systems. Fundamentally, a tool for designing the SIMPLE-based chips was developed which provides the design parameters to be used to achieve the targeted flow rate. This consists in an analytical model that was derived and used to validate the assumption that the flow rate is dependent on the porous material geometry and not channel geometry and porous volume. Eventually, they compared the experimental results with the model results. The model results obtained were in good agreement with the experimental results. Their work is currently published in the journal, Sensors and Actuators A: Physical. For instance, the authors confirmed that the sample liquid flow rate was dependent on the porous material shape and independent on the porous material volume and channel geometry. The model distributions enabled prediction of the pumping behaviors for the design of several chips. Additionally, the model provided precise design parameters for achieving the targeted flow rate thus avoiding the initially used trial and error method. This reduced tremendously the design and optimization time to achieve the final chip configuration.

The University of Leuven scientists presented an analytical approach and showed its feasibility for designing microfluidic chips based on the SIMPLE concept. It also gives more insight into the pumping process by predicting the channel flow rate. Altogether, the study will advance the implementation of the concept in more complex microfluidic devices for various applications.

SIMPLE analytical model for smart microfluidic chip design - Advances in Engineering

SIMPLE analytical model for smart microfluidic chip design - Advances Engineering

Videos illustrating the SIMPLE Technology:

SIMPLE working principle (pull pump),  iSIMPLE working principle (push pump), combination of SIMPLE and iSIMPLE to shuttle a sample liquid.

About the author

Ir. Francesco Dal Dosso holds an MSc in Biomedical Engineering (2013, Polytechnic of Milan, Italy) and he achieved his PhD in Bioscience Engineering at KU Leuven (Belgium) in November 2018. He is involved in developing the innovative SIMPLE and iSIMPLE self-powered microfluidic platform for lab-on-a-chip applications towards point-of-care test. His research involves integration of different bioassays (e.g. digital assay, enzymatic) on the SIMPLE and iSIMPLE concepts towards detection of different biomarkers.

About the author

Ir. Yura Bondarenko holds an MSc in Bioscience Engineering (2017, KU Leuven). During his postgraduate education, he contributed to the development and practical application of the SIMPLE and iSIMPLE platform. Currently, he is researching the integration of full-field optical coherence microscopy with microfluidics to develop a non-invasive, label-free continuous biomonitoring platform.

About the author

Dr. Tadej Kokalj received a B.Sc. in Physics at the Faculty of Mathematics and Physics and Ph.D. degree at the Faculty of Mechanical Engineering, University of Ljubljana, Slovenia in 2001 and 2006, respectively. He was a postdoctoral researcher in the field of material science at the Institute of Metals and Technology, Ljubljana, Slovenia and at the Materials Engineering Department, KU Leuven, Belgium. In 2011, he was a Fulbright visiting scholar in bio-microfluidics in BioPOETS group at UC Berkeley, USA.

Currently he is a senior scientist at the Institute of Metals and Technology, Slovenia and a scientific collaborator of the Biosensors group, KU Leuven, Belgium. His main research interests are surface structuring and functionalization, microfabrication for microfluidics, and disposable, self-powered systems for point-of-care diagnostics.

About the author

Prof. Dr. Ir. Jeroen Lammertyn holds an MSc in Bioscience Engineering (KU Leuven, Belgium) and a MSc in Biostatistics (UHasselt, Belgium), as well as a PhD in Bioscience Engineering (2001, KU Leuven, Belgium). From 2002 he worked as postdoctoral researcher and spent one year at Pennsylvania State University, USA. Since 2005 he is appointed Full Professor and Head of the division of Mechatronics, Biostatistics and Sensors of the Biosystems Department of the KU Leuven.

His main research interests include biosensors development, nanohybrid materials, micro- and nanofluidics and bioassay development. He is author of 200+ peer reviewed research papers, and acts as reviewer for many international journals.

Reference

Dal Dosso, F., Bondarenko, Y., Kokalj, T., & Lammertyn, J. (2019). SIMPLE analytical model for smart microfluidic chip design. Sensors and Actuators A: Physical287, 131-137.

Go To Sensors and Actuators A: Physical

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