MEMS-based Lab-on-chip platform with integrated 3D and planar microelectrodes for organotypic and cell cultures

Résumé

The presented thesis is focused on the development and validation of lab on chip (LOC) platforms for their application on Biology, Medicine and Biomedicine, particularly those related with cells and tissues cultures, as well as their treatment through electrostimulation and their electrical behavior. Nowadays, research works focused on the development of LOCs have significantly increased, mostly thanks to its high versatility, which involves countless applications. Among all this applications, those related with Biology and Medicine are becoming more and more important. The integration of sensors, actuators, microfluidic circuits and electronic circuits in the same platform allows the fabrication of systems with lots of applications. This thesis is focused on the development of platforms for in vitro cultures of cells and tissues, to monitor their behavior and interact with the biological samples. The importance of in vitro cultures lies on the study of cells and tissues proliferation and morphology or performing drug delivery experiments. In this respect, through LOC technologies, it would be possible to model human diseases in vitro, in order to improve the development of new drugs and advance personalized medicine. Thus, the possibility of carrying out medium-long term cultures on platforms without the need of any expensive equipment, such as CO2 incubators, with software and monitoring, implies a qualitative step forward in the development of in vitro cultures. Within this framework, the work related to this thesis is presented. This PhD has been undertaken in the Microsystem group of the High School Engineering of the University of Seville. The structure of this thesis is organized in such a way that, all along the text, the different aspects previously described are explained in detail. Firstly, a brief introduction about MEMS technology and the basic principles of Microfluidics is presented. Due to this work has been developed in a multidisciplinary environment, this section becomes necessary in order to give a wide view to those non XXVII XXVIII Abstract directly familiarized with these fields. Subsequently, a description of the state of the art is presented, including LOC systems and their applications in Biology, Medicine and Biomedicine, taking special attention to those applications related to organotypic and cell cultures. After the introduction and the state of the art of the framework of this thesis, the results obtained are presented. In the first part of this PhD, the development, fabrication and characterization of the autonomous system for culture and electrostimulation of tissues is described. This system includes a lab on PCB (LOP) composed of a 3D microelectrode array (MEA), with gold wires of 25 µm on transparent substrate, sensors and actuators, together with a microfluidic platform made of PMMA and PDMS. This LOP allows to maintain the appropriate temperature conditions to carry out medium-long term cultures without using a CO2 incubator, as well as its continuous monitoring through an inverted microscope, thanks to the transparent materials used for its fabrication. This system is connected to an external electronic circuit and a software to control the whole system, including the electrostimulation of the biological sample. After explaining the design and the innovative fabrication process of the LOP, the experimental results are presented. Firstly, it has been demonstrated the suitability of this system to perform organotypic cultures of mice retinas for longer than 7 days, obtaining similar results to the same samples, but cultured through traditional methods. In addition, it has been provided neuroprotection to mice retinal explants with the retinitis pigmentosa (RP) disease through the electrostimulation of the samples, being able to slowdown the degeneration of the retinas caused by RP.