A compression transmission device for the evaluation of bonding strength of biocompatible microfluidic and biochip materials and systems

Abstract

Bonding of a variety of inorganic and organic polymers as multi-layered structures is one of the main challenges for biochip production even to date, since the chemical nature of these materials often does not allow easy and straight forward bonding and proper sealing. After selection of an appropriate method to bond the chosen materials to form a complex biochip, function and stability of bonding either requires qualitative burst tests or expensive mechanical multi-test stations, that often do not have the right adaptors to clamp biochip slides without destruction. Therefore, we have developed a simple and inexpensive bonding test based on 3D printed transmission elements that translate compressive forces via manual compression, hand press or hydraulic press compression into shear and tensile force. Mechanical stress simulations showed that design of the bonding geometry and size must be considered for bonding tests since the stress distribution thus bonding strength heavily varies with size but also with geometry. We demonstrate the broad applicability of our 3D printed bonding test system by testing the most frequent bonding strategies in combination with the respective most frequently used biochip material in a force-to-failure study. All evaluated materials are biocompatible and used in cell-based biochip devices. This study is evaluating state-of-the-art bonding approaches used for sealing of microfluidic biochips including adhesive bonding, plasma bonding, solvent bonding as well as bonding mediated by amino-silane monolayers or even functional thiol-ene epoxy biochip materials that obviate intermediate adhesive layers.

High‐Resolution 3D Printing of Dual‐Curing Thiol‐Ene/Epoxy System for Fabrication of Microfluidic Devices for Bioassays

“…In comparison to the thermal bond strength of 0.31 MPa of our developed dual‐curing material, the commercially available dual‐curing material OSTEMER 322 shows an increased bond strength of 1.0 MPa. [ 50 ] However, the thermal bond strengths of common thermoplastic materials for microfluidic devices such as PS–PS (0.38 MPa), [ 51 ] PMMA–PMMA (0.19 MPa), [ 52 ] or PET–PET (0.25 MPa) [ 53 ] as well as an acrylate/epoxy‐based dual‐curing adhesive (0.26 MPa) [ 54 ] are in the same range as our developed material. Thus, the adhesive‐free dry bonding of the presented dual‐curing system provides a simple method for fabrication of microfluidic devices with suitable bond strength.…”

Robust and Seamless Integration of Thiol‐Ene‐Epoxy Thermosets with Thermoplastics and Glass as Hybrid Microfluidic Devices Suitable for Drug Studies

“…These methods, however, entail the risk of introducing new substances that can alter biocompatibility, surface energy, monomer leaching and optical properties. [25,26] The uneven coating and unwanted filling of microchannels by the interfacing materials are further obstacles commonly associated with such methods. [27] With the recent emergence of microphysiological systems (MPS) that are based on compartmentalized perfused devices of often hybrid nature, [28,29] the need for appropriate back-end processing techniques has been brought to the spotlight.…”

“…These methods, however, entail the risk of introducing new substances that can alter biocompatibility, surface energy, monomer leaching and optical properties. [ 25,26 ] The uneven coating and unwanted filling of microchannels by the interfacing materials are further obstacles commonly associated with such methods. [ 27 ]…”

Step-by-step : A microfluidic (PDMS) staircase device for size sorting microparticles down to 25 µm using a 3D-printed mold

“…However, being a PDMS/Glass device means that the device may delaminate and will require another round of plasma to be covalently reattached. [18] We then check the size-sorting device for three applications: detecting parasite eggs, microplastics, and zooplankton from water bodies. The eggs can also be identified on a less than 10 Euro ESP32 microscope that was developed during this research (Figure S3 and S4).…”