Methods in Molecular Biology (2022) 2436: 27–38

DOI 10.1007/7651_2021_397

© Springer Science+Business Media, LLC 2021

Published online: 27 April 2021

Fabrication Protocol for Thermoplastic Microfluidic

Devices: Nanoliter Volume Bioreactors for Cell Culturing

Elif Gencturk, Senol Mutlu, and Kutlu O. Ulgen

Abstract

Microfluidic devices consist of microchannels etched or embossed into substrates made of polymer, glass or

silicon. Intricate connections of the microchannels to reactors with some smart mechanical structures such

as traps or curvatures fulfil the desired functionalities such as mixing, separation, flow control or setting the

environment for biochemical reactions. Here, we describe the fabrication methods of a thermoplastic

microbioreactor step by step. First, material selection is made, then, production methods are determined

with the equipment that can be easily procured in a laboratory. COP with its outstanding characteristics

among many polymers was chosen. Two types of microbioreactors, with and without electrodes, are

designed with AutoCAD and L-edit softwares. Photolithography and electrochemical wet etching are

used for master mold preparation. Thermal evaporator is employed for pure chromium and gold deposition

on COP substrate and etchants are used to form the interdigitated electrodes. Once the master mold

produced, hot embossing is used to obtain the designed shape on drilled and planarized COP. Cover COP,

with or without electrodes, is bonded to the hot embossed COP via thermo-compression and thermoplas-

tic microfluidic device is realized. Tubings are connected to the device and a bridge between the macro and

micro world is established. Yeast or mammalian cells labeled or tagged with GFP/RFP on specific gene

products are loaded into the microfluidic device, and real time data on cell dimensions and fluorescence

intensity are collected using inverted fluorescence microscope, and finally image processing is used to

analyze the acquired data.

Key words COP, Deposition, Etching, Hot embossing, In-house fabricated microfluidic device,

Photolithography, Thermo-compression Bonding

1

Introduction

Unprecedented success of the microelectronics industry on the

integration of micro- and nano-sized devices at very high densities

using fabrication methods, such as lithography, thin film deposition

and etching, paved the way for the development of microfluidic

platforms [1]. The driving force for these technologies has always

been to miniaturize desktop sized biochemical analysis systems.

The main advantage of miniaturization in these systems is the

reduction in the sample and reagent volume. Microfluidic devices

also provide faster heat transfer, shorter process times and better

automation. Biological and medical applications in cell culture,

drug screening, point-of-care (POC) systems adopts microfluidics

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