Overview
The advancing miniaturization in many application fields leads to an increasing performance in their linked processes and devices. This is also valid for microfluidics which shows a lot of advantages in opposite to macroscopic methods as reduced consumption of reagents, an improved surface to volume ratio and corresponding with this an improved heat-mass-transfer. Consequently the usage of microfluidics is especially appropiate in mixing processes, the analysis of chemical or biological reactions or in cell culture very powerful. The development and design of microfluidic chipsystem is a very challenging task and requires knowledge in fluid dynamics, material science as well as the processes that shall be emedded in the microfluidic system. For the creation of chipsystems, this page shall give a little overview of methods we use for development.
Design and Validation
The design process starts with creating a 3D-model of the chip systems by using CAD-Programs. For optimization of structures we are using numerical simulation, which is conducted with ANSYS CFX. This program serves as a basis for geometrically optimization during product engineering and enables deeper insights of specifically used effects within the microfluidic surrounding. Thereby coincidentally computational fluid dynamics in combination with statistical methods enable a cost-effective geometry optimization before the final production process and significantly reduce the need for a prototype of every design version. For validation of functionality, prototypes are built with additive manufacturing processes and tested.
| Simulated mixing process in a micromixer using Ansys CFX | 3D printed micromixer prototype for validation of simulation results |
Manufacturing
After verification of utilization, the microfluidic chipsystems are manufactured by external partners that use up-to-date technologies to achieve a high accuracy even in the smallest features. Technologies used for fabrication of the chipsystems are amongst other things injection molding for plastic parts or sintering for ceramics.
Bonding Methods
Since high complex three-dimensional structures can't be integrated into a single part, the chipsystems are made of different layers. For bonding of plastic parts, several methods primarly based on adhesives have benn established in our group. This includes for instance the usage of thermal lamination films that are structed by laser cutting or the application of UV-curable, low viscosity adhesives. To get reproducible bonding results, we developed a bonding platform that allows a electronic control of applied pressure during bonding with an integrated pressure sensor and the regulation of temperature by a silicone-heater that can warm up to 200 °C.
| Bonding system to connect microfluidic chip parts | Bonding holder for fixing chip parts |
Current Developments
Our current development is a platform for optimization of tumor therapy, which includes two chipsystems. One chipsystem deals with the characterization of the tumor by staining of tumor markers via immunohistochemistry. With this chipsystems it is possible to stain up to six tumor markers simultaniously with one sample only. When the tumor is characterized, it is important to choose the proper cytostatic drugs for efficient therapy. But since not all tumors are homogenious, it ist important to check the chemosensitivity of the tumor to possible cytostatic drugs. This investigation can be done with the second chip system. Here, up to eight cytostatic drugs can be applied independendly to tumor cells of the patient. To check parameters like cell viability, gold electrodes and circuits are integrated in the chipsystem to the application of ECIS, which offers a high sensitive non-invasive method to check cell parameters. With the help of project partners, the chipsystems are embedded into a platform that offers a tumor therapy in short time. Another recent developed microfluidic chip is based on ceramics offers the possibility for photochemical nanoparticle synthesis. Irradiation can be applied by an integrated glas window, whereas heating of the fluids inside the chip is done by inductive heating with integrated metal foils inside the chip.
| CAD-Model of the Lab-on-a-Chip-System for tumor therapy optimization | CAD-Model of microfluidic chip system for immunohistochemistry |