Prof. Dr. Rainer Adelung
Institute for Materials Science
Kiel University, Germany

3D printed organic-inorganic and nano-macro scale hybrids for sensor and biomedical applications

Remaining challenges in additive manufacturing are still the are combination of various material classes like metals, semiconductors, ceramics and organic materials ranging from graphene to biological tissue.  Furthermore, combining macroscopic devices with nanoscale precision structuring with macroscopically expanded applications and devices  is another challenge. These demanding combinations are required by many applications in different fields that demand a high amount of functionality, e.g. for sensor applications  or biomedical engineering.  The presentation covers beside recent developments some solution ideas to these challenges by introducing 3d printed devices and application examples. As demonstrators for sensors, chemiresistive sensor arrays that employ semiconductor nanoscale features in microscopic devices [1] and sensors for diabetes detection [2] based on acetone sensing in ppm levels by printing mixed semiconductor oxides [2]. To illustrate applications on the biomedical side where, e.g., nanoscale protein structures, hydrogels and semiconductors are combined, a 3 d printed smart wound scaffolds with a light triggered growth factor release and antibacterial activity is explained and shown [3].

Prof. Dr. Jasmin Aghassi
Institute of Nanotechnology (INT)
Karlsruhe Institute of Technology, Germany

Logic and memory devices realized by 2D/3D-printing of functional materials

The talk will give an introduction into device fabrication and electrical characterization of inkjet-printed passive and active devices including electrolyte-gated transistors based on indium oxide semiconductors, diodes and integrated circuits [1,2]. In addition, memory devices such as resistive switching devices based on Ag/ZnO/Au sandwich structures [3] will be presented. These reveal  high ON/OFF ratios up to 10^7, excellent retention behavior exceeding 10^4 seconds and no obvious degradation after 50 switching cycles at low operation voltage around 1 V. These features and the ability to form logic and memory devices renders the technology useful for novel low power applications in the area of embedded sensors, hardware security and bioelectronics.

[1] Progress Report on “From Printed Electrolyte‐Gated Metal‐Oxide Devices to Circuits”, Cadilha Marques, G.; Weller, D.; Erozan, A. T.; Feng, X.; Tahoori, M.; Aghassi‐Hagmann, J., 2019. Advanced Materials, 31 (26), 1806483, doi:10.1002/adma.201806483

[2] Hybrid low-voltage physical unclonable function based on inkjet-printed metal-oxide transistors, Scholz, A.; Zimmermann, L.; Gengenbach, U.; Koker, L.; Chen, Z.; Hahn, H.; Sikora, A.; Tahoori, M. B.; Aghassi-Hagmann, J., 2020. Nature Communications, 11 (1), 5543. doi:10.1038/s41467-020-19324-5

[3] Inkjet-printed bipolar resistive switching device based on Ag/ZnO/Au structure, Hongrong Hu, Alexander Scholz, Surya Singaraju, Yushu Tang, Gabriel Cadilha Marques, and Jasmin Aghassi-Hagmann, 2021. Applied Physics Letters, 119 (11), 112103–1. doi:10.1063/5.0058526

Prof. Dr. Christopher Barner-Kowollik
Institute of Chemical Technology and Polymer Chemistry
Karlsruhe Institute of Technology, Germany
Queensland University of Technology, Australia

Dynamic Functional Photoresists for Light Driven Additive Manufacturing

The lecture will provide an overview of our most recent results in the realm of designing photoresist that feature advanced properties after being printed via two photon 3D laser lithography or one photon printing techniques. The properties particularly include post-printing adaptability as well as degradability by various outer stimuli – including by the mildest trigger of all, darkness. A particular emphasis will be placed on illustrating the advanced photochemical concepts that drive modern resist design and how they interface with specific applications

Maria Farsari, Ph.D.
Institute of Electronic Structure and Laser

Laser-based additive micromanufacturing for cell growth

A critical component for successfully engineering complex 3D tissue from a cell source is the production and utilisation of the appropriate 3D scaffold. Indeed, cells seeded on a flat surface grow typically in a monolayer
fashion, while 3D cell cultures can only be achieved via their growth in a 3D micro-environment. The success of
these scaffolds in their use for tissue engineering is critically dependent on their mechanical and surface properties, and microstructure.

In this seminar, I will present our latest results into combining laser-based additive manufacturing, mechanical metamaterials, and novel photopolymers, attempting to address some major tissue engineering challenges.

Larisa Florea, Ph.D., Assistant Professor
Trinity College, Dublin, Ireland

4D Micro-structures – Functionality with a splash of colour

Direct laser writing (DLW) by multi-photon polymerisation represents an attractive route towards the creation of 3D assemblies from a wide range of materials. This talk will focus on the use of soft polymers and responsive materials for the realisation of 4D micro-structures that can respond to external stimulation, actuate on demand, and sense and report on their local chemical environment. Inspired by nature’s structurally coloured materials, we recreate the vividness of natural structural colouration via DLW in responsive polymer systems. The presence of the soft stimuli-responsive matrix enables us to accurately modulate the perceived colour across the visible and NIR range, in response to light, temperature, humidity, and chemical environment.

Dr. Kerstin Göpfrich
Max Planck Institute for Medical Research
Heidelberg University, Germany

3D direct laser writing in synthetic cells

Towards the ambitious goal of manufacturing synthetic cells from the bottom up, various cellular components have already been reconstituted inside of lipid vesicles. However, once encapsulated, the positoning of these components is challenging. Here, by using two-photon 3D laser printing, 2D and 3D hydrogel architectures were manufactured with high precision and nearly arbitrary shape inside of preformed giant unilamellar lipid vesicles (GUVs). The required water-soluble photoresist is brought into the GUVs by diffusion in a single mixing step. Crucially, femtosecond two-photon printing inside the compartment does not destroy the GUVs. Beyond this proof-of-principle demonstration, early functional architectures were realized. In particular, a transmembrane structure acting as a pore was 3D printed, thereby allowing for the transport of biological cargo, including DNA, into the synthetic compartment. Furthermore, we attempt to develop new types of photoresists alongside DNA-based architectures, with which we can realize more complex functions inside of synthetic cells. These experiments show that two-photon 3D laser microprinting can be an important addition to the existing toolbox of synthetic biology.

Referenz: https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.202106709

Maria Guix, Ph.D.
Institute of Bioengineering of Catalonia, Spain

Bringing color and life to 3D robotics

One of the main challenges in the field of synthetic and biological microrobots is the development of robust control systems to achieve the desired guidance and/or actuation.[1] Reaching full automation, where the robot’ path and actuation are predetermined and programmed, is still one of the main challenges in the micro and nanomotors’ community. By integrating colored tracking fiducials in the micrometric robot’ body, it is possible to develop less computationally expensive color-based tracking algorithm, even providing real-time data to the end user for finer robot control.[2] By using 3D printing techniques, we achieved the integration of structural color in micrometric robotic systems, obtaining well-defined features with vivid colors useful for vision-based algorithms and non-toxic. [3] This fabrication approach is of great interest for its potential scale-up in other robotic platforms for automation purposes, as well as for improved manipulation in tissue engineering applications and mechanobiology studies.

On the other hand, the integration of cells in robotic systems can directly provide some of the desired capabilities inherent to such living entities, including self-healing, energy efficiency, high power-to-weight ratio, adaptability, or bio-sensing capabilities.[4] We develop a millimeter-sized skeletal-muscle based biobot with an integrated compliant skeleton based on a 3D-printed serpentine spring [5]. Such configuration not only provides mechanical integrity to the bio-derived system, but also self-stimulation in absence of any external electrical input, useful for training purposes to achieve an increased force output. Simulations of the mechanical properties to obtain the optimal geometrical stiffness were carried out. Also, force studies [6] demonstrated an enhanced output force when dynamic mechanical training was taking place. Two different motion mechanisms (swimming and coasting) were demonstrated for the same biobot configuration, being the fastest skeletal muscle-based swimming bio-hybrid robot up to date by several orders of magnitude (791x). Also, mechanical self-stimulation allows to control a defined self-assembly geometry of the cell-laden scaffold, useful to explore new living robot configurations.

The versatility of 3D printing techniques provides a useful toolbox to develop robotic systems, allowing not only an easy integration of distinctive elements for control purposes, but also the fabrication of dynamic elements with self-training capabilities that when combined with 3D cell-laden scaffold they result in more advanced and highly functional robotic platforms.

[1] Guix, M., Mayorga-Martinez, C. C., Merkoçi, A. (2014) Chem. Rev., 114, 6285−6322.
[2] Guix, M., Wang, J., An, Z., Adam, G., Cappelleri, D. J. (2018) IEEE Robot. Autom. Lett., 3, 3591-3597.
[3] Koepele, C. A., Guix, M., Bi, C., Adam, G., Cappelleri, D. J. (2020) Adv. Intell. Syst, 2, 1900147.
[4] Appiah, C., Arndt, C., Siemsen, K., Heitmann, A., Staubitz, A., Selhuber-Unkel, C. (2019) Adv. Mater. 31, 1807747.
[5] Guix, M., Mestre, R. Patiño, T., De Corato, M., Fuentes, J., Zarpellon, G., Sánchez, S. (2021) Sci. Robot. 6, eabe7577.
[6] Mestre, R., Patiño, T., Barceló, X., Anand, S. Pérez-Jiménez, A., Sánchez, A. (2019) Adv. Mater. Technol. 4, 1800631.

Richard Hague, Ph.D., Professor
University of Nottingham, United Kingdom

Additive Manufacturing 2.0: Moving beyond geometry for the printing of functional, multi-material products

Though capable of tremendous geometrical design freedoms, conventional Additive Manufacturing (AM) is mainly restricted to “passive”, structural components. This presentation will overview the emerging area of “multifunctional” AM, where multiple materials are co-deposited to enable the move beyond geometry, thereby enabling the printing of complex, functionalized, “active” printed devices. The talk will detail the ongoing work within the Centre for Additive Manufacturing (CfAM) at the University of Nottingham where significant research efforts into next-generation, multifunctional AM is being undertaken. Principally funded by EPSRC and working with key industry, this research is exploiting novel techniques for the co-deposition of both structural and functional materials for electronic, pharmaceutical and biological structures and devices over varying length scales.

Prof. Dr. Uli Lemmer
Light Technology Institute & Institute of Microstructure Technology, Germany

Karlsruhe Institute of Technology

Nanophotonic Devices by Inkjet Printing

Inkjet printing (IJP) is a versatile method for additive manufacturing of electronic and optoelectronic devices with a typical spatial resolution on the order of 30 microns. For realizing photonic nanostructures using this approach, the deposited materials have to be controlled on a subwavelength length scale. Here, we demonstrate that this can be realized, both, in vertical and in lateral direction. Using the spontaneous phase-separation of two polymers from a common ink, we realize quasi-periodic and disordered assemblies of light scatterers. The phase separated nanostructures feature sizes that can be tuned from a few microns down to the sub-100 nm level. Applications are in the field of photonic sensors and  optoelectronic thin film devices. An even more precise control is necessary for realizing one-dimensional photonic crystals (dielectric mirrors) by IJP. Such an approach enables digitally controlled dielectric mirror pixels for various opto-electronic applications.

Prof. Dr. Pavel Levkin
Institute of Biological and Chemical Systems
Karlsruhe Institute of Technology, Germany

3D printing of inherently nanoporous polymers via polymerization-induced phase separation: properties and applications

3D printing offers enormous flexibility in fabrication of polymer objects with complex geometries. However, it is not suitable for fabricating large polymer structures with geometrical features at the sub-micrometer scale. Porous structure at the sub-micrometer scale can render macroscopic objects with unique properties, including similarities with biological interfaces, permeability, special wettability and extremely large surface area, imperative inter alia for adsorption, separation, sensing or biomedical applications. Here, we introduce a method combining advantages of 3D printing via digital light processing and polymerization-induced phase separation, which enables formation of 3D polymer structures of digitally defined macroscopic geometry with controllable inherent porosity at the sub-micrometer scale. We demonstrate the possibility to create 3D polymer structures of highly complex geometries and spatially controlled pore sizes from 10 nm to 1000 µm. Produced hierarchical polymers combining nanoporosity with micrometer-sized pores demonstrate improved adsorption performance due to better pore accessibility and favored cell adhesion and growth for 3D cell culture due to surface porosity. This method extends the scope of applications of 3D printing to hierarchical inherently porous 3D objects combining structural features ranging from 10 nm up to cm, making them available for a wide variety of applications.

Mangirdas Malinauskas, Ph.D.

Group of Nanophotonics, Laser Research Center, Physics Faculty,
Vilnius University, Lithuania

Mesoscale laser 3D printing: from renewable plant-based resins to crystalline inorganics

An ultrafast laser mesoscale lithography will be presented rediscovering underlying photo-physio-chemical reactions determining its technical applications. A current progress in state-of-the-art and potential in 3D as well as 4D printing of diverse materials ranging from biocompatible, biodegradable and renewable organics to amorphous, ceramic and crystalline inorganics will be covered. Technology’s applications towards prototyping and producing bio-medical implants, micro-optical and nano-photonic components as well as creating micro-fluidic sensors will be shown. A special emphasis on the development and applications of microfabricated structures for life-sciences will be given, namely customization of laser direct write lithography-made 3D scaffolds for optimized in vivo outcome.  Furthermore, the possibility to employ the technique for precision additive manufacturing out of plant-based resins and pure inorganics will be demonstrated. Finally, some unique functional properties of selected prototypes will be provided in detail validating their high efficiency performance and resiliency under harsh conditions.

[1] E. Skliutas, M. Lebedevaite, E. Kabouraki, T. Baldacchini, J. Ostrauskaite, M. Vamvakaki, M. Farsari, S. Juodkazis, M. Malinauskas, Polymerization mechanisms initiated by spatio-temporally confined light, Nanophotonics 10(4),1211-1242 (2021).
[2] L. Jonušauskas, D. Gailevičius, S. Rekštytė, T. Baldacchini, S. Juodkazis, M. Malinauskas, Mesoscale Laser 3D Printing, Opt.   Express 27(11), 15205-15221 (2019).
[3]   J. Mačiulaitis, S. Rekštytė, M. Bratchikov, R. Gudas, M. Malinauskas, A. Pockevičius, A. Ūsas, A. Rimkūnas, V. Jankauskaitė, V. Grigaliūnas, R. Mačiulaitis, Customization of Direct Laser Lithography-based 3D Scaffolds for Optimized in Vivo Outcome, Appl.  Surf.  Sci. 487, 692-702 (2019).
[4] M.  Lebedevaitė, J.  Ostrauskaitė, E.  Skliutas, M. Malinauskas, Photoinitiator free resins composed of plant-derived monomers for optical 3D μ-printing, Polymers 11(1), 11 (2019).
[5] E.  Skliutas, M.  Lebedevaitė, S.  Kašėtaitė, S.  Rekštytė, S.  Lileikis, J.  Ostrauskaitė, and M. Malinauskas, A Bio-Based Resin for a Multi-Scale Optical 3D Printing, Sci. Rep., 10, 9758 (2020).
[6] A. Butkutė, L. Čekanavicius, G. Rimšelis, D. Gailevičius, V. Mizeikis, A. Melninkaitis, T. Baldacchini, L. Jonušauskas, M. Malinauskas, Optical Damage Thresholds of Microstructures Made by Laser 3D Nanolithography, Opt.  Lett. 45(1), 13-16 (2020).
[7]   D. Gailevičius, V. Padolskytė, L. Mikoliūnaitė, S. Šakirzanovas, S. Juodkazis, and M. Malinauskas, Additive-Manufacturing of 3D Glass-Ceramics down to Nanoscale Resolution, Nanoscale Horiz. 4, 647-651 (2019).
[8] S. Varapnickas, S.-C. Thodika, F. Moroté, S. Juodkazis, M. Malinauskas, E. Brasselet, Birefringent optical retarders from laser 3D-printed dielectric metasurfaces, Appl. Phys. Lett. 118, 151104 (2021).

Shoji Maruo, Ph.D., Professor
Yokohama National University in Tokyo, Japan

Multi-material micro-stereolithography using multiple droplets of photocurable materials

In recent years, multi-material additive manufacturing has attracted attention as a method for the integrated manufacture of highly functional devices. Several micro-stereolithography techniques have been demonstrated to fabricate micro-scale multi-material 3D structures using one-photon or two-photon polymerization. Multi-material micro-stereolithography methods can be classified as microfluidic, tank-based and droplet-based methods with respect to the material exchange method. The droplet-based method has the advantage of easy material exchange and low material wastage during exchange. In this talk, I will introduce lab-made multi-material micro-stereolithography systems using multiple droplets of photocurable materials. Using the single-photon system, multi-color polymer structures were fabricated using photocurable resins with different colors. Multi-material glass structures were also fabricated using photocurable silica slurries. In addition, a multi-material two-photon lithography system was also developed using multiple droplets. Micro-optical elements such as diffraction gratings and GRIN lenses were fabricated using photocurable resins with different refractive indexes. These multi-material micro-stereolithography systems will be useful for producing functional microdevices including micro-optical elements, metamaterials and scaffolds.

Virgilio Mattoli, Ph.D
Istituto Italiano di Tecnologia, Italy

Toward MEMS direct fabrication by two photon lithography

In the last twenty years, Micro Electro-Mechanical Systems (MEMS) produced a great impact on different market areas, due to the important technological applications ranging from automotive and consumer electronics to biology, medicine and energy, and new applications are emerging daily. The performances of such systems rely on both the design and the intrinsic properties of the constituent materials, that have to be processed with sub-micron resolution, high precision and reproducibility. Two photon lithography, making possible the realization of outstanding three-dimensional structures with nanoscale features, could be a key technology toward the direct fabrication of MEMS devices. In this talk I’ll present the perspectives, the requirements and the challenges of this approach, focusing on recent results of our group in term of MEMS fabrication and integration. In particular, the fabrication of integrated conformal metal paths by self-shadowing, the integration with silicon electronics and the ubiquitous transfer of 2PP microstructures will be presented in details.

Christophe Moser, Ph.D., Associate Professor
EPFL Lausanne, Switzerland

Volumetric printing by reverse tomographic projections in non transparent resins

Antoine Boniface1, Jorge Andres Madrid Wolff1, Paul Delrot2, Damien Loterie2, and Christophe Moser1
1 Laboratory of Applied Photonics Devices, School of Engineering, Ecole Polytechnique Fédérale de Lausanne, CH-1015, Lausanne, Switzerland.
2 Readily3D, CH-1015, Lausanne, Switzerland

In volumetric additive manufacturing, an entire three-dimensional object is simultaneously solidified by
irradiating a liquid photopolymer volume from multiple angles with dynamic light patterns [1,2,3]. This technique
based on 3D light dose accumulation produces the object in 3D without any layers and support structures. The
printing time is only a few tens of seconds for several cubic centimeters with excellent part fidelity. To date, 3D
object using only transparent resins have been demonstrated. We will show new results of 3D prints in nontransparent resins which opens new material possibilities.


[1] Loterie D., Delrot P. and Moser C., Volumetric 3D Printing of Elastomers by Tomographic Back-Projection, DOI:
10.13140/RG.2.2.20027.46889, 2018.
[2] Loterie D., Delrot P., and Moser C., High-resolution tomographic volumetric additive manufacturing, Nature Communications, Vol. 11,
[3] Bernal P. N., Delrot P., Loterie D., Li Y., Malda J., Moser C., Levato, R., Volumetric Bioprinting of Complex Living‐Tissue Constructs
within Seconds, Advanced Materials, 2019.

Prof. Dr. Bastian Rapp

Laboratory of Process Technology | NeptunLab
Department of Microsystems Engineering (IMTEK)
Albert-Ludwigs University of Freiburg, Germany

Next generation 3D Printing: The emergence of enabling materials

3D printing is the manufacturing revolution of the 21st century. The invention of printing by Johannes Gutenberg over 500 years ago, the ability to generate, replicate and disseminate artifacts has changed human history significantly. Recent decades have seen printing moving from two-dimensional to three-dimensional. Just as the printing press enabled individuals to share, distribute and archive information, printing in 3D will enable to share, improve and generate objects from digital designs via the internet. This technology has the potential to eventually resolve the boundaries between classical industries specialized on manufacturing and the end user which classically only used objects generated by someone else.

Additive manufacturing and 3D printing have seen significant improvements in terms of processing and instrumentation with the aim of increasing the complexity of the objects constructible, increasing resolution and lateral dimensions as well as speed of manufacturing. Interestingly, the choice of materials has not been increasing significantly. Most 3D printing techniques still use polymers or composites (e.g., with ceramic particles). Selective Laser Sintering (SLS) is the only process which has been extended to include metals. One of the oldest materials mankind has used was missing: Glass. Account of man-made objects in glass date back to 5000 BC. Glass has numerous advantageous properties including unmatched optical properties, mechanical, thermal as well as chemical stability to name but a few.

In 2016 we have contributed a prototyping process in glass which uses a glass nanocomposite which can cured by light and sequentially thermally annealed to result in highly-transparent fused silica glass. With a contribution in Nature, this process was finally successfully transferred to 3D printing. Recently, we demonstrated industrial-scale polymer replication using this technology in an article in Science. This closes an important gap in the material palette of modern 3D printing processes enabling, for the very first time, the free-form generation of highly transparent fused silica glass by a state-of-the-art 3D printing process. This has major implications for many applications ranging from 3D printing of complex lenses for smartphone cameras, next-generation microprocessors, all the way to ornaments or intricate glass panels used in buildings.

Dr. Marta Ruscello
Forward AM, BASF 3D Printing Solutions, Germany

The importance of Design for Additive Manufacturing: Creating Performance Materials using Computer Aided Engineering

With the establishment and further advancement of Additive Manufacturing (AM), the knowledge
about material and design – and their interplay – constantly evolves. Knowing that choosing the right
material for each application has proven to be essential, there is another important, if not decisive,
factor: the design of the part.
Virtual Engineering plays a vital role in Additive Manufacturing. How successfully a 3D printed part
performs depends on two fundamental elements – its material and its geometry. Thinking of the fact
that even the strongest material is prone to break when being applied in a poor design underlines the
importance of well-thought applied simulation tools in AM – ensuring the right design for each
individual application.
Leveraging clinical and individual data, digital simulation tools enable engineers to digitally generate,
simulate, and manufacture finely tuned lattices. This opens up the possibility of significantly enhancing
3D printed parts for various industry verticals, such as automotive, medical or consumer goods.
This talk will provide new insights into how BASF 3D Printing Solutions GmbH leverages the simulation
tool Ultrasim® to push lattice innovations forward. It will be examined how to identify the right lattice
for each individual project and application – providing enhanced mechanical properties and better
protection, cushioning, and comfort when compared to traditional foam.

Sourabh K. Saha, Ph.D. Assistant Professor
Georgia Institute of Technology, Atlanta, USA

High-throughput two-photon lithography via temporally focused light sheets

High-throughput fabrication techniques for generating arbitrarily complex three-dimensional structures with nanoscale features are desirable across a broad range of applications including healthcare, transportation, and computing. Two-photon lithography (TPL) is a promising additive manufacturing (AM) technique that relies on nonlinear light absorption to fabricate complex 3D structures with polymeric nanoscale features. However, commercially available serial point-by-point writing scheme of TPL is too slow for many applications. We have developed a high-throughput nanoscale AM technique based on parallelization of TPL. Our technique has increased the processing rate by a thousand times while preserving the nanoscale feature sizes. It relies on simultaneous spatial and temporal focusing of an ultrafast laser to implement projection-based layer-by-layer printing using arbitrarily patterned light sheets. This talk will focus on how we broke the traditional tradeoff between rate and feature size – a tradeoff that had persisted in the field for more than two decades. Our method allows access to difficult to explore regions in the design space, increasing both the potential for cost-effective high-throughput processing and the geometric complexity of the printed objects.

Prof. Dr. Thomas Scheibel
Bayreuth University, Germany

Biofabrication using spider silk proteins

Proteins reflect one fascinating class of natural polymers with huge potential for technical as well as biomedical applications. One well-known example is spider silk, a protein fiber with excellent mechanical properties such as strength and toughness. We have developed biotechnological methods using bacteria as production hosts which produce structural proteins mimicking the natural ones [1, 2]. Besides the recombinant protein fabrication, we analyzed the natural assembly processes and we have developed spinning techniques to produce protein threads closely resembling natural silk fibers. In addition to fibers, we employ silk proteins in other application forms such as hydrogels, particles or films with tailored properties, which can be employed especially for biomaterials applications [3].

We could e.g. design spider silk-based sheets and scaffolds that prevent adherence of microbes. Without adherence biofilm formation cannot occur, which lowers the frequency of infections in surgical patients. However, the spider silk sheets and scaffolds do not kill any cells. Unlike current treatments they prevent infestation to begin with. The designed spider silk scaffolds are even bio selective, meaning that this designer silk repels microbes while allowing human cell attachment and proliferation [4]. Spider silk hydrogels can be even employed as bioinks for biofabrication (i.e. 3D bioprinting together with cells) [5], but also non-aqueous solvents can be used to 3D-fabricate spider silk scaffolds [6]. Their elastic behavior dominates over the viscous behavior over the whole angular frequency range with a low viscosity flow behavior and good form stability. No structural changes occur during the printing process, and the hydrogels solidify immediately after dispense plotting. Due to the form stability it was possible to directly print multiple layers on top of each other without structural collapse. Cell-loaded spider silk constructs can be easily printed without the need of additional cross-linkers or thickeners for mechanical stabilization. Encapsulated cells show good viability in such spider silk hydrogels. Exemplarily, we use 3D-printed spider silk scaffolds for the growth of heart muscle patches [7, 8] or for generating nerve guiding conduits [9, 10].

[1] Heidebrecht, A., Scheibel T. (2013). Recombinant production of spider silk proteins. Adv. Appl. Microbiol. 82, 115-153
[2] Saric, M., Eisoldt, L., Döring, V., Scheibel, T. (2021) Interplay of Different Major Ampullate Spidroins During Assembly and Implications for Fiber Mechanics. Advanced Materials 33, 2006499
[3] Aigner, T.B., DeSimone, E., Scheibel T. (2018) Biomedical applications of recombinant silk-based materials. Advanced Materials 30, 1704636
[4] Kumari, S., Lang, G., DeSimone, E., Spengler, C., Trossmann, V., Lücker, S., Hudel, M., Jacobs, K., Krämer, N., Scheibel, T. (2020) Engineered spider silk-based 2D and 3D materials prevent microbial infestation. Materials Today, 41, 21-33
[5] Schacht, K., Jüngst, T., Schweinlin, M., Ewald, A., Groll, J., Scheibel, T. (2015) Biofabrication of cell-loaded, 3D recombinant spider silk constructs. Angew. Chem. Int. Ed., 54, 2816-2820
[6] Neubauer, V., Trossmann, V., Jacobi, S., Döbl, A., Scheibel, T. (2021) Aqueous-Organic Solvent Derived Recombinant Spider Silk Gels as Depots for Drugs. Angew. Chem. Int. Ed., 60 DOI:10.1002/anie.202103147
[7] Petzold, J. Aigner, T., Touska, F., Zimmermann, K., Scheibel, T., Engel, F. (2017) Surface features of recombinant spider silk protein eADF4(κ16)-made materials are well-suited for cardiac tissue engineering. Adv. Funct. Mat. 27, 1701427
[8] Kramer, J., Aigner, T., Petzold, J., Roshanbinfar, K., Scheibel, T., Engel, F. (2020) Recombinant spider silk protein eADF4(C16)-RGD coatings are suitable for cardiac tissue engineering. Sci Reports 10, 8789
[9] Pawar, K., Welzel, G., Haynl, C., Schuster, S., Scheibel, T. (2019) Recombinant Spider Silk and Collagen-Based Nerve Guidance Conduits support Neuronal Cell Differentiation and Functionality in vitro. ACS Appl. Bio Mater. 2, 4872-4880
[10] Aigner, T.B., Haynl, C., Salehi, S., O’Connor, A., Scheibel, T. (2020) Nerve guidance conduit design based on self-rolling tubes. Materials Today Bio 5, 100042

Prof. Dr. André Studart
Department of Materials
ETH, Switzerland

3D Printing of Bioinspired Materials

Biological materials exhibit heterogeneous architectures that are tuned to fulfill the functional demands and mechanical loading conditions of their specific environment. Examples range from the cellulose-based organic structure of plants to collagen-based skeletal parts like bone, teeth and cartilage. Because they are often utilized to combine opposing properties such as strength and low-density or stiffness and wear resistance, the heterogeneous architecture of natural materials can potentially address several of the technical limitations of artificial implants or composites in general. However, current man-made manufacturing technologies do not allow for the level of composition and fiber orientation control found in natural heterogeneous systems. In this talk, I will show that 3D printing routes using self-assembling inks offer an exciting pathway for the fabrication of biologically-inspired materials with unprecedented heterogeneous architectures and functional properties.

Prof. Dr. Franziska Thomas
Institute of Organic Chemistry
Heidelberg University, Germany

Exploring small β-sheet protein folding motifs as a model systems for the design of miniaturized proteins

Franziska Thomas, Heidelberg/D, T. L. Pham, Heidelberg/D, C. L. Lindner, Heidelberg/D, F. Häge, Heidelberg/D, M. Kovermann, Konstanz/D, Jun.-Prof. Dr. Franziska Thomas, Universität Heidelberg, Im Neuenheimer Feld 270,
69120 Heidelberg/D

De novo designed biomolecules have a tradition of being applied as models to mimic natural systems or to create new functional assemblies, which work under physiological conditions. In this context, small protein folding motifs are highly interesting as the function of ideally every single amino acid residue is understood and the impact of modifications on the structure and/or function easy to determine. Due to the wellunderstood sequence-to-structure relationships, the coiled-coil motif is probably most frequently applied in synthetic-biological endeavors; however, other protein folding motifs more and more come to the fore.
Our research focuses on small β-sheet motifs, more specifically the WW domain and the SH3 domain, which recognize proline-rich peptide sequences. Using rational design or combinatorial approaches, we try to install reactivity or binding properties. In the case of the WW domain, we have designed a generic scaffold based on sequencestructure relationships that will be functionalized to bind, for example, metals, phosphorylated residues or carbohydrates. Such biomimetic peptide receptors are intended for applications in synthetic biology or biofunctionalization of materials.

Luis Fernando Velásquez-García, Ph.D.
Microsystems Technology Laboratories
Massachusetts Institute of Technology, USA

Efficient, compact, complex hardware via additive manufacturing

Microsystems harness component miniaturization to attain better performance, looking to replicate the success of integrated circuit (IC)’s very large-scale integration (VLSI). For the longest time, most microsystems have been made in the cleanroom using the very same tools employed to manufacture IC VLSI chips; this problematic because semiconductor foundries (i) greatly restrict the materials and geometries that can be processed, (ii) use very expensive machinery that needs to be controlled by highly trained personnel, and (iii) are geared for 24/7 production of large quantities of archetypical goods. Consequently, the commercialization of many great microsystem ideas has been hindered, either due to lack of adequate performance or to the cost and time required to produce the devices. Additive manufacturing (AM) is the layer-by-layer fabrication of objects using a computer-aided design (CAD) model; AM has associated exciting possibilities such as monolithic creation of complex, multi-material parts, customization, and low per-unit cost for small-batch to mid-batch production. Currently, commercial 3D printers create solid objects by layering volume elements (voxels) with characteristic dimensions on the order of tens of microns or smaller, making possible to implement true microsystems. This talk will go over selected examples of additively manufactured developed by the Velasquez-García Group @ MIT; in many cases, the devices operate better than the state of the art, or are the first of their kind, as a semiconductor cleanroom version is unfeasible or impractical. These results suggest that AM is a toolbox that can provide high-performance engineering solutions, with manufacturing times and costs better aligned to a wider range of business models compared to the semiconductor cleanroom.

Joel K. W. Yang, Ph.D., Assistant Professor
Singapore University of Technology and Design, Singapore

Structurally Colorful Optical Elements With Sub-Micron 3D and 4D Printing

Multiple pigments each relying on specific chemical compositions are needed to generate a full range of color. In contrast, structural colors allow one to potentially achieve a wide color gamut using only a single material, or a pair of materials. This shift from material requirements comes at the expense of lithographic needs. Hence, precision tools and processes are needed to produce the requisite nano-geometry for the desired colors. In this talk, we review some concepts of color generation in metals and dielectrics, and discuss key approaches to generating structural color using two-photon polymerization lithography (TPL). A method to overcome the resolution limitations of TPL to produce colorful 3D photonic crystals will be presented. In addition, we present insight into a simpler nanopillar geometry that exhibits the ability to be individually colorful, i.e. not relying on diffractive effects.