Overcoming a serious manufacturing constraint

Additive manufacturing (AM) utilizing two-photon polymerization lithography (TPP) has elevated in utilization in trade and analysis. At the moment, a serious constraint of TPP usually and particularly of the fabric IP-Q (Nanoscribe GmbH, Germany) is the customers’ restricted entry to data about materials properties. As a result of nature of the method, the elastic properties specifically rely not solely on the utilized materials but in addition on construction measurement, course of, and fabrication parameters. For instance, earlier than analysis not too long ago printed within the Journal of Optical Microsystems, no diploma of conversion (DC) and Younger’s modulus (E) values for IP-Q had been reported.

As a result of nature of the method, the elastic properties specifically rely not solely on the utilized materials but in addition on construction measurement, course of parameters, and hatch technique. A standard method makes use of a mix of Raman spectroscopy and nanoindentation to characterize the DC of monomer to polymer measurable by way of Raman spectroscopy, which might then be associated to the mechanical habits of the fabric, measurable by way of nanoindentation.

Ongoing analysis on acoustic metagratings and metamaterials fabricated on MEMS would profit from optimized elastic parameters to supply adjustability of the acoustic habits, as they have an effect on the attribute acoustic impedance straight. AM encompasses processes with which objects may be created three-dimensionally from a technical drawing. The info are despatched to an AM system, which then performs the fabrication. AM by way of TPP is predicated on selective curing of a liquid precursor to create strong buildings inside a drop of monomer. Afterwards, the leftover liquid is washed away. Well-known TPP purposes are optical sub-micron buildings, the place the photoresist IP-Dip (Nanoscribe GmbH, Germany) is often utilized. The extra not too long ago developed photoresist IP-Q was designed by the identical producer for bigger purposes, e.g. mounts, molds, and structural metamaterials. Pattern buildings from every of the 2 photoresists had been produced in parameter sweeps. This permits the comparability of course of parameters to the ensuing traits. Raman spectroscopy was employed, which is a non-contact evaluation technique for materials characterization during which monochromatic mild is scattered off the fabric.

The reflection contains not solely the irradiated wavelength but in addition Raman scattering. The attribute peaks of the Raman scattering spectrum can be utilized for the identification of chemical substances. In our work, it was used to find out the ratio of monomer to polymer—or DC—within the TPP samples.

Micro- and nanoindentation had been used to check the mechanical properties of the samples. A tough tip whose mechanical properties are identified is pressed into the pattern whose properties are unknown. From the slope of the load vs. displacement curve, E values had been computed.

Lastly, parameter sweeps of cuboid pattern buildings fabricated utilizing TPP had been investigated throughout the parameters laser energy and scan velocity to search out dependent properties. The employed photoresists had been examined utilizing Raman spectroscopy to search out the DC of monomer to polymer, and subsequently micro- or nanoindentation had been used to search out E.

For IP-Dip, the attained DC and E ranged from 20 to 45% and 1 to 2.1 GPa, respectively. The outcomes had been in comparison with studies discovered within the literature. For IP-Q, the attained DC and E ranged from 53 to 80% and 0.5 to 1.3 GPa, respectively. The characterised properties of IP-Q manifest as the present state of information of the fabric.

“By this implies, providing an method to optimize elastic parameters of TPP-fabricated buildings will likely be helpful for varied ongoing analysis subjects. A promising software for this technique is the characterization of the elastic parameters of acoustic metagratings and metamaterials fabricated on MEMS. These gadgets can subsequently be applied beneficially in life science, mobility, and industrial purposes,” mentioned Severin Schweiger of Fraunhofer Institute of Photonic Microsystems and Brandenburg College of Know-how in Germany.

Supplied by
SPIE–Worldwide Society for Optics and Photonics