Frequently Asked Questions
HETEROMERGE offers complete multi-material solutions for 3D printing of functional microsystems. We rely on 2-photon-polymerization based 3D direct laser writing. This is one of the finest and at the same time fastest 3D printing processes today.
In this section, we answer frequently asked questions about our currently available MergeOne add-on and our multi-material technology for two-photon polymerization (2PP) systems.
Questions about the product
The setup takes about 30-45 minutes for an inexperienced user. Experienced users can reduce this time to below 30 minutes.
The dismantling of the printhead, including cleaning, takes about as long as the setup. Cleaning essentially involves flushing the fluidic components, usually with isopropanol and nitrogen or compressed air. Only simple manual operations by the user are required here. Cleaning is the main part of the dismantling process and can be carried out by experienced users in less than 30 minutes. If the MergeOne system is used intensively, we recommend cleaning after approx. 1 week of use or as soon as a long print job with this duration has been completed.
We provide an intensive user training. The installation and de-installation is a quick and safe procedure. Parts of the MergeOne system can be safely kept installed as a permanent addition to the system. As mentioned before, there is no invasive modification of the 2PP system we upgraded. That means normal 2PP printing and usage of the printer is not impacted at all.
We do not use pumps in our system. We use lab-supplied pressurized gas (preferably nitrogen) and vacuum along with pressure regulators to operate our system. If preferred by the customer, stand along compressors and pumps can be used to provide pressure and vacuum. We recommend placing them at a sufficient distance from the printing tool if needed.
Questions about material exchange
The exchange time depends on the viscosity of the printing material and the geometric complexity of the print object. For materials with low viscosity, the exchange time is usually less than 5 min. As the viscosity increases, the exchange time also increases, so that for materials with medium and very high viscosity, it is between 5 min and 50 min. The highest viscosity we have tested so far is beyond 30 mPas.
Residual material should remain in the material reservoirs. The provided small volume bottles are UV-tight and can be stored according to the manufacturer’s recommended storage conditions for the printing materials being used. Other fluidic components should be cleaned regularly after use.
You can use reservoirs filled at maximum with 10 ml printing material at the moment for process and user convenience minimizing refill steps. The current system can be operated with as low as 2 ml filling of the reservoir. There is a procedure that can work with less than 1 ml of printing material. We are currently also working on reservoirs with about 1 ml capacity for applications where small volumes are relevant. The consumption was discussed in a separate question.
The typical viscosities for which recipes are available are between 500 mPas and 50 Pas.
General questions about the printing
Currently, the MergeOne system is available for 25x objectives from ZEISS. With this, writing fields up to 400 µm are possible. Larger structures are assembled using the respective concepts offered by the printer (stitching). Prints with heights up to the millimeter range are possible. The smallest structures are in the range of 1 µm due to the used objective. Smaller and larger structures will be available in perspective with new printheads as suitable objective adapters.
Questions about printing optical structures
The interface represents a transition area of numerous properties. The most critical effect would be delamination between different material sections. The advantage of the in situ material exchange is that it works without developing as an intermediate step. This means that it can be assumed that a maximum number of reactive groups can be achieved at the interface and is thus available for high adhesion of the materials. In addition, mixed phases may be present in a spatially very limited area, which can also contribute to improved adhesion. It is not expected that this transition region will impact optical performance. In principle, high adhesion can only be achieved if compatible materials are used in terms of polymerization mechanism as well as chemical composition. For most commercial materials as well as the materials of HETEROMERGE this is given. For non-compatible materials as well as materials with significantly differing material shrinkage, despite optimized exposure parameters, improved adhesion can be achieved by a matching layer or certain mechanic support structures for optics.
There are materials such as Ormocere® which are already established in industrial use, especially at high temperatures (e.g. reflow processes), and which deliver very good properties. Those materials can also be used for the typical range of temperature of electronic devices.
Printing can take place at module level or at wafer level. In this case, the laser diode or at least the coupling facet/active material might come into direct contact with the printing material. In principle, however, printing can also be done on corresponding module carriers, which are then aligned with the laser diode for sensitive active regions. In the latter case, however, the packaging density is significantly lower.
We have printed current examples for optical and biological applications. For the proof of functionality, we are currently working intensively with corresponding customers and partners. These results will soon be available to the public, and we will publish them accordingly.