Exploring laser welding for microfluidic chips
Laser welding and microfluidics: precision engineering at the core of Mora Group’s expertise
Microfluidics is evolving rapidly, driven by major challenges in healthcare and diagnostics. MORA Group is rising to meet these challenges by combining its expertise in plastic injection molding and laser welding. Through the insights of Vincent Collard, discover how laser welding is becoming a strategic lever in the assembly of microfluidic chips.
Hello Vincent, could you briefly introduce yourself?
I’m Vincent Collard, Technical Director at MORA Group and a mechanical engineer graduated from UTC Compiègne.
After an initial experience in subcontracting, I spent 15 years in the automotive industry, designing engine sensors and mechatronic systems for manufacturers such as PSA, Renault, BMW, and Ford. I led teams and managed projects from design through to production launch.
I then took on new challenges in the renewable energy sector, overseeing large-scale projects for EDF and Aéroports de Paris.
Today, I bring this expertise to MORA’s clients, supporting them in their most complex projects with precision and high standards.
Vincent, could you explain what laser welding of microfluidic chips made of COC involves?
To begin with, COC (Cyclic Olefin Copolymer) is a plastic material particularly well-suited for microfluidic devices. It stands out for its excellent optical transparency, biocompatibility, and low chemical leachability. These properties make it a credible and increasingly common alternative to glass, which has historically been used for such applications. With performance characteristics similar to glass, COC is becoming a strategic choice for the design of microfluidic chips.
What is a microfluidic chip, and what are its main applications?
Microfluidic chips are small devices used to handle very small volumes of liquids. They are at the core of numerous applications in medical diagnostics and biology. Today, this technology is experiencing significant growth, particularly in the areas of screening and analytical testing.
Microfluidic chips operate somewhat like the COVID test cassettes that most people are familiar with. The chips are inserted into diagnostic devices, just like the COVID cassettes, to deliver fast and accurate analysis results. The tested samples typically consist of drops of blood or other bodily fluids, and the results indicate the presence or absence of specific pathogens.
At Mora, we are directly involved in the manufacturing of these microfluidic chips. Our clients are primarily the manufacturers of diagnostic devices, with whom we collaborate to produce microfluidic chips tailored to meet strict technical and medical requirements.
These chips are integrated into diagnostic systems that use a wide range of technologies, depending on the specific application — including infrared detection, ultrasound, or genetic analysis. Their strength lies in their ability to detect elements at the molecular level using very small sample volumes: a single drop of blood, sweat, or another bodily fluid is often enough.
The applications are numerous: disease detection, genetic screening, biomarker research, as well as quality control in the food industry—such as detecting traces of gluten. This wide range of uses makes microfluidic chips a key enabler in the advancement of bioproduction and personalized diagnostics.
The fundamental principle of microfluidics is based on manipulating extremely small amounts of liquid through networks of microchannels. When a sample—such as a drop of blood—enters a microfluidic chip, it is divided into a multitude of micro-droplets, sometimes numbering in the tens of thousands. Each droplet can then be analyzed individually. This process enables highly precise analyses, often supported by statistical models, to confirm or rule out the presence of a biomarker, disease, or specific agent.
There is a wide variety of microfluidic chips, with different architectures depending on their intended use. However, the principle of sample fragmentation and multipoint analysis remains central to many applications.
What types of microfluidic chips does MORA Group manufacture?
The microfluidic chips we work on incorporate complex networks of microchannels, which are essential for guiding the liquid sample, fragmenting it into micro-droplets, or directing it toward a targeted analysis zone.
These components require an extremely high level of precision. Some applications demand the fabrication of channels as small as 20 to 40 microns, with dimensional tolerances within just a few microns. This degree of accuracy is what enables diagnostic machines to deliver reliable results.
We have notably developed microfluidic chips for the IPGG (Pierre-Gilles de Gennes Institute), a leading research organization in France specializing in microfluidics. The institute collaborates with a wide range of partners across various application fields. Our work has included not only the manufacturing of high-precision microfluidic chips but also the laser welding assembly of components.
Qu’est ce que l’IPGG
IPGG is a French interdisciplinary research center specialized in microfluidics and nanofluidics. It is affiliated with PSL University and brings together teams from ESPCI, ENS, Institut Curie, and Chimie ParisTech. IPGG combines both fundamental and applied research, relying on a multidisciplinary team of physicists, biologists, chemists, and engineers to develop new microfluidic technologies
Indeed, in all applications, microfluidic chips must be hermetically sealed without obstructing the channels or compromising their functionality.
Pourquoi souder une puce microfluidique ?
To begin with, laser welding technology is not new; it was already in use more than twenty years ago, particularly in the automotive industry for assembling sensors. Even then, it proved to be an effective alternative to other assembly methods, including in complex and automated architectures.
When it comes to microfluidic chips, however, the level of precision required changes drastically. Accuracy becomes critical. The components are smaller, the tolerances much tighter, and every weld must be perfectly controlled to ensure the sealing of microchannels and the reliability of diagnostic performance.
The challenge, in this context, isn’t the welding technology itself—but rather adapting it to micro-scale assemblies, where the slightest deviation can compromise the system’s functionality.
The manufacturing of a microfluidic chip typically begins with the injection molding of a base component, which serves as the main support. This is where the microchannels are formed with the high level of precision needed for the system to function correctly.
But the molded part alone is not enough! To become operational, it must be sealed. A flat film is added on top as a cover to close off the microchannels. The goal is to achieve a perfectly airtight assembly that allows for controlled fluid circulation. This step requires a welding or bonding process that can join the two components without deforming the delicate structures of the molded part.
Why use laser welding for this type of product?
Until a few years ago, microfluidic chips were mainly assembled using chemical processes, particularly adhesive bonding. These techniques had several drawbacks: long processing times, complexity in industrial-scale production, and—most importantly—the use of potentially harmful chemicals. This poses a significant issue in medical environments, where material purity is critical.
In this context, Mora made the strategic decision to offer laser welding as an assembly solution. This technology offers several advantages: it is fast, clean, and easily scalable for industrial production, and it does not introduce any foreign materials. Only the properties of the original plastic components are utilized. This last point is particularly important for diagnostic and biomedical applications, where any external contamination must be avoided. Laser welding has therefore established itself as a reliable, clean solution that meets the strict requirements of the sector.
At Mora, we validated this approach through a Proof of Concept (POC), which allowed us to demonstrate that laser welding can achieve all three critical objectives: perfect sealing in highly targeted areas, reliable mechanical strength, and—most importantly—strict compliance with the micro-precision required by the chip’s structure.
It’s a true technical challenge, as the welding must be done without obstructing the surrounding microchannels. Some areas of the part feature channels as small as 20 microns in height, with tolerances of just a few microns in both width and depth. The welding process must therefore be extremely localized, precisely controlled, and highly repeatable.
Another major advantage of this process is the ability to integrate inline camera-based inspection, enabling automatic quality control of welds in critical areas.
Today, we are already using highly specialized laser welding machines. However, as volumes increase, our goal is to integrate them into fully automated production lines to ensure scalability, repeatability, and productivity.
What are the different types of laser welding used for this kind of application?
In the field of laser welding for assembly, three main technologies stand out, each suited to specific needs depending on the geometry of the parts and the sensitivity of the areas that must be preserved:
- Contour laser welding: In this approach, the laser beam follows a precise path around the weld area. The laser moves along the microchannels, following a defined trajectory. This method is well-suited for complex shapes and highly localized welds.
- Mask-based laser welding: This technique involves projecting a laser beam across the entire surface, while protecting sensitive zones with a copper mask. The mask shields areas such as fluidic channels from exposure to heat. The laser sweeps the surface, heating only the unmasked regions. This method is particularly suitable for assemblies that require strict preservation of functional areas..
- Hybrid technology: There are also combined processes that leverage the advantages of both contour and mask-based welding, offering greater flexibility and precision depending on the application.
To optimize the laser welding process, Mora chose to use mask-based assembly.
Could you tell us a bit more about mask-based laser welding?
To ensure a reliable and repeatable assembly, Mora has implemented a tightly controlled laser welding process. It all begins with precision fixturing: the molded component is first positioned on a dedicated support, then the sealing film is placed on top. This step is critical, as it requires strict flatness tolerances.
To meet these demanding requirements, Mora developed a dedicated film-guiding system to ensure perfect flatness of the entire assembly prior to welding. A glass plate is then applied to apply uniform pressure across the stack. The copper mask, which defines the weld zones, is integrated into this glass plate.
The laser scan is carried out with extreme precision: only the areas exposed by the mask are welded. To achieve this, the mask itself must be machined with even greater precision than the final part, as beam diffraction can occur through the thickness of the mask—requiring exceptionally high-quality machining.
This level of precision led Mora to collaborate with specialized partners for both mask fabrication and laser welding. Thanks to this rigorous approach, the results achieved fully met expectations in terms of accuracy, with tolerances kept within just a few microns.
Today, the laser welding assembly process developed by Mora is capable of meeting a wide range of industrial needs—particularly in the demanding fields of medical diagnostics and microfluidics. Few players have mastered these technologies with such precision, giving Mora a unique position in this high-precision market.
Are there many of you who have mastered this technology?
Not really! That’s precisely why Mora is actively involved in a consortium of French stakeholders united around a common goal: to revive and structure a true microfluidics industrial sector in France. While our country has long been at the forefront of research in this field, that leadership hasn’t always translated into local industrialization.
The technology exists, the expertise is there—but what needs to be strengthened now is the production ecosystem. The COVID-19 pandemic and the rise of genetic testing have acted as catalysts for awareness, highlighting the strategic importance of these technologies for both public health and industrial sovereignty.
At Mora, this ambition is reflected in close partnerships with research organizations such as the Pierre-Gilles de Gennes Institute, in collaboration with prestigious institutions like the Institut Curie. This dialogue between fundamental research and industrial know-how is key to developing concrete, locally manufactured solutions that meet today’s medical and technological challenges.
How do you see the future of this technology that Mora has mastered so well?
Over the past two years, the field of microfluidics has experienced real momentum. Whether in research institutions or, more recently, in the industrial sector, initiatives are multiplying—driven by healthcare, innovation, and sovereignty challenges. The ambition is clear: to position France as a major player in this technology, building on its internationally recognized excellence in medical research.
MORA Group is fully committed to this dynamic—both in laser welding for assembly and in plastic injection molding. The upcoming projects already present new, even more demanding technical constraints that will require us to explore advanced injection technologies.
Each new development is a true challenge, especially in terms of precision, but it’s also what fuels our passion and commitment. Microfluidics is a field where every detail matters—and it is precisely in this level of rigor that MORA Group finds its purpose and legitimacy.