55 sealed fuel cells ready to be assembled into a high-performance stack. The fast curing provides high-speed assembly, with high chemical resistance against sulphuric acid and deionised water. This gives the maximum design freedom thanks to liquid application with volumetric dosing for consistent, uniform beads. Inkjet printing Another way to apply the adhesive and other materials is using inkjet printing technology to provide accurate dispensing of the adhesives in complex patterns. “This is a digital replacement for dispensing systems that scales more easily to large-scale manufacturing,” said Ben Hartkopp, founder and head of research and IP at Quantica in Germany. “One of the first ultra-high-viscosity applications was for printing the channel plates in fuel cells.” This used a UV-activated material from Henkel as an adhesive and gasket, providing sub-millimetre placement. “With an inkjet, you can print exactly to a certain distance to the edge, so that the material exactly conforms to the geometry, by adjusting the drop density on the fly, even with batch variations, so there is controllability,” he said. To do this requires a different type of printing technology. “We built our own print head and our own actuators,” he said. This provides 8000 drops/nozzle (8 kHz frequency) with 96 nozzles in the print head. The print heads can be stacked, which gives a single pass with inline speeds of 1.0– 1.2 m/s and higher if more print heads are used, so there is no throughput bottleneck for printing complex geometries. The drop sizes range from 250 up to 600 pl and Quantica can easily vary the nozzle size, he said. “We use laser ablation for the forming of the nozzles, and the actuator is agnostic to the nozzle size – so we can go down to 30 up to 90 μm – depending on the fluid characteristics,” he said. The print head uses an actuated channel with forced ejection – so there is no specific fluidic geometry – rather than using a resonant frequency that is droplet-size dependent. “This means we have a larger deflection that pressurises an area around the nozzle so we can change the nozzle size easily,” said Hartkopp. “This forced ejection is more stable for the edge issues and across batch variations – that’s a huge fundamental advantage, particularly for adhesives.” This also increases the potential for adding larger particles up to 9 μm. Quantica designs the print head, which is manufactured by a partner. Quantica has developed a dispensing system that can be used for evaluation that includes UV LEDs for curing the adhesive if necessary and can be integrated into the equipment. The print heads can also be used by integration partners. “We work with integrators and we have developed our own material supply system with all the electronics that can be integrated into production lines. We also supply the print engine that can be integrated with any trigger signal system. “With the system integrators, we talk about the spacing of the initiators for the UV for the epoxy to activate, but here you need to look at the time delay and the speed of the line. We have 365 and 405 nm wavelength UV available because we use them internally, but they might not be up to spec for line speeds of 2.8 m/s, but we can also use off-the-shelf UV units. “We provide some specific fluidic properties as a reference – we have heating integrated into the print head to reduce the viscosity from room temperature – if we get it down to 250 mPa s, then we can inkjet it with a 9 μm particle,” he said. “We prefer higher surface tension but we have printed 20 mN/m, we have printed liquid metal, and we can print Newtonian and non-Newtonian materials. “Most of the materials typically have a visco-relaxive response, so the higher the frequency, the more like a solid they perform – that is a problem for traditional inkjet printers. These are highly particle-loaded or resins with large molecular weights or aqueous polymers with a high concentration.” Another advantage of the inkjet E-Mobility Engineering | January/February 2026 An inkjet print head for printing high-viscosity adhesives for fuel cells (Image: Quantica)
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