Additive manufacturing of piezoelectric barium titanate

Additive manufacturing of piezoelectric barium titanate-bioactive

glass composite scaffolds

Christian Polley1, Thomas Distler2, Rainer Detsch2, Aldo R. Boccaccini2, Hermann Seitz1

1Microfluidics, University Rostock, Rostock, Germany 2Institute of Biomaterials, Friedrich Alexander University Erlangen Nuremberg, Erlangen, Germany

Introduction

Piezoelectric bone replacement materials represent a novel and innovative therapeutic option for the treatment of bone

defects. The stimulation of bone by piezoactive materials promises to induce the ingrowth of natural bone to the implant.

This study aims to combine electrical-stimulation capacity and bioactivity by using material compostions constisting of

barium titanate (BaTiO3) and bioactive glass (45S5 bioglass®) for the three-dimensional (3D) printing of scaffolds.

Methods

Composite scaffolds consisting of BaTiO3 and 45S5 were 3D-printed based on various material compositions using a

binder jetting process. The scaffolds were sintered after 3D-printing and subsequently analysed regarding their porosity,

the distribution of 45S5 particles, their mechanical and piezoelectric properties.

Results

Piezoelectric composite scaffolds were successfully printed with material combinations consisting of 5 wt% and 15 wt%

bioactive glass. The samples show high density and mechanical compressive strength of 40 to 60 MPa after sintering.

Due to the dense microstructure, d33 values of up to 25 pC/N can be achieved, which is a multiple of natural bone. The

piezoelectric constant d33 can be adjusted by choosing appropriate polarization parameters such as temperature and po-

larization time. Scanning electron microscopy investigations revealed bioactive glass on the surface of the scaffolds and

bioactivity after incubation in simulated bodyfluid after 28 days. .

Conclusion

The 3D-printing of piezoelectric and bioactive scaffolds shows great promise for use as bone graft substitutes. The inves-

tigations shown here represent the basis for future research in the exciting field of functional piezoelectric biomaterials.

S434Abstracts – BMT 2021 – Hannover, 5 – 7 October • DOI 10.1515/bmt-2021-6072 Biomed. Eng.-Biomed. Tech. 2021; 66(s1): S434–S438 • © by Walter de Gruyter • Berlin • Boston

Deformation measurements with a flexible pharyngeal phantom

Alina Ibbeken, Institute of Medical Engineering, Universität zu Lübeck, Lübeck, Germany, [email protected]

Fenja Zell, Institute of Medical Engineering, Universität zu Lübeck, Lübeck, Germany, [email protected]

Christina Hagen, Institute of Medical Engineering, Universität zu Lübeck, Lübeck, Germany, [email protected]

Sven Seele, HICAT GmbH, [email protected]

Ulrike Grzyska, Department of Radiology and Nuclear Medicine, Universitätsklinikum Schleswig-Holstein, Lübeck, Ger-

many, [email protected]

Alex Frydrychowicz, Department of Radiology and Nuclear Medicine, Universitätsklinikum Schleswig-Holstein,

Lübeck, Germany, [email protected]

Armin Steffen, Department of Ear, Nose and Throat Medicine, Universitätsklinikum Schleswig-Holstein, Lübeck, Ger-

many, [email protected]

Thorsten M. Buzug, Fraunhofer Research Institution for Individualized and Cell-Based Medical Engineering IMTE and

Institute of Medical Engineering, Universität zu Lübeck, Lübeck, Germany, [email protected]

Introduction

The experimental examination of obstructive sleep apnea (OSA) can improve and support diagnosis and therapy. Defor-

mation measurements with flexible pharyngeal phantoms of OSA patients can provide important information about the

causes and pathophysiological mechanisms of OSA. A better understanding of this information could potentially lead to

improvements of existing treatments.

For this reason, we fabricated an anatomical upper airway phantom with additive manufacturing based on magnetic res-

onance imaging data of an OSA patient. The quality of the fabricated phantom was evaluated regarding its deviation from

the digital model. Furthermore, we present a setup to perform deformation measurements which can be acquired using

computed tomography (CT).

Methods

A flexible anatomical phantom of the upper airway of an OSA patient was fabricated using Fused Deposition Modeling

(FDM) and silicone casting techniques. The Youngs modulus of the used silicone Sylgard 527 is chosen according to

elasticity properties of pharyngeal soft tissue reported in the literature. The quality of the fabricated phantom was evalu-

ated using a CT scan and comparing the segmented soft tissue replica and airway geometry to the digital model to

measure the deviation. Therefore, the distance between each point of the mesh of the segmentation to the nearest point of

the digital model was calculated and the mean absolute distance was calculated.

To use the phantom for deformation measurements, a setting consisting of a flow pump, a flow sensor, pressure sensors

and a piping system was designed. The resulting deformation of the soft tissue replica during flow can be examined using

CT.

Results

A comparison of the digital model with a CT scan of the fabricated phantom evaluates the quality of the phantom. It is

shown that the deviation of the soft tissue replica and the airway structure is in the range of image resolution with a mean

absolute distance of 0.9 mm ± 0.7 mm and 0.3 mm ± 0.3 mm.

Conclusion

A workflow for the fabrication of a flexible anatomical upper airway phantom was developed and evaluated. A setup to

perform deformation measurements was developed and is used in current work.


mailto:[email protected]








Laser Bioprinting

Lothar Koch, Institut für Quantenoptik, Leibniz Universität Hannover, Hannover, Germany, [email protected]

Andrea Deiwick, Institut für Quantenoptik, Leibniz Universität Hannover, Hannover, Germany, [email protected]

hannover.de

Boris Chichkov, Institut für Quantenoptik, Leibniz Universität Hannover, Hannover, Germany, [email protected]

hannover.de

Introduction

For engineering of fully functional tissue, complex three-dimensional compositions of living cells and biomaterials need

to be generated. Even before printed tissues and organs can be implanted in patients, there are several applications for

printed cell structures in research. Conventional cell studies in Petri dishes (in vitro) are not suitable for simulating the

complex interactions in three-dimensional tissues and in cell microenvironments like those in the body. Cells react fun-

damentally different in 3D. Printed 3D cell patterns can fill the gap between conventional cell cultures in vitro and ani-

mal models in vivo.

Methods

Laser Bioprinting is one of the techniques applied for tissue printing, combining high resolution with the ability to print

high cell densities and high viscous materials. In the process, a tissue is not printed directly, but rather a 3D pattern of

dissociated cells that then form a tissue over the course of days or weeks, so that this temporal progression must be tak-

en into account as a fourth dimension.

Results

Many types of cells from different organs, stem cells and microorganisms have already been printed without harming

them and simple 3D tissues have been successfully generated with this method. Examples of printed multicellular 3D

constructs for studying cell-cell interactions and printed tissue will be presented and challenges towards printed organs

will be discussed.

Conclusion

Laser bioprinting is proving to be a very versatile and promising technique for generating complex 3D cell-based con-

structs and tissues. However, much remains to be done before fully functional tissue or entire organs can be produced.

In particular, a complex and perfusable vascularization corresponding to the natural model has not yet been realized.

Once these challenges are overcome, printed tissue may replace animal testing in the chemical, pharmaceutical, and

cosmetic industries, and later printed organs could also address the shortage of donor organs.


Extrusion-based MatrixPrinting for glass, metal and polymers Grace Vera, Freiburg Material Research Center, 79110 Freiburg, Germany, [email protected]

Silvio Tisato, Freiburg Material Research Center, 79110 Freiburg, Germany, [email protected]

Dorothea Helmer, Department of Microsystems Engineering IMTEK, University of Freiburg, 79110 Freiburg, Germany,

[email protected]

Introduction

Extrusion-based volumetric additive manufacturing methods are a category of 3D printing techniques in which inks are

deposited into suitable supporting matrices. The combination of a special printing matrix with a suitable ink allows the

printing of complex 3D structures under “zero gravity conditions” without the need for supporting structures. This reduces

the amount of material and time needed to complete the printing process and and increases the freedom of design. These

methods are mainly known from bioprinting, whith soft materials and hydrogels. Here we show the extension of the

material palette to the fabrication of smooth glass, metal and polymer structures using the MatrixPrint printing platform.

Methods

The MatrixPrint printing platform comprises of a delta printer system which was modified with a high-precision extru-

sion-system for liquid inks. The rheological properties of several inks and matrices were tested and adjusted to fit the

requirements for printing. Parts were analyzed in terms of their material and surface properties.

Results

We have engineered several matrices to fit the printing inks to produce smooth parts from metals, polymers and glass.

Besides suitable rheological properties the surface energy match between matrix and ink is important for achieving

smooth parts. Here we show the fabrication of smooth structures by means of the MatrixPrint method, using an ink based

on the Glassomer technology.

Conclusion

Volumetric printing without supporting structures greatly widens the design space and enables especially smooth parts

by matching of the properties of ink and matrix. We show that fabrication of glass, metal and polymer structures is feasible

with high accuracy, towards direct printing of channels and reactors with integrated electronics.





Modulating the reaction of primary human immune cells through precise design of 3D printed scaffolds

Tina Tylek, Chair for Functional Materials in Medicine and Dentistry at the institute of Functional Materials and Biofab-rication & Bavarian Polymer Institute, Uni-versity of Würzburg, Pleicherwall 2, 97070 Würzburg, Germany, [email protected]

Matthias Ryma, Chair for Functional Materials in Medicine and Dentistry at the institute of Functional Materials and Biofabrication & Bavarian Polymer Institute, Uni-versity of Würzburg, Pleicherwall 2, 97070 Würzburg, Germany, [email protected]

Carina Blum, Chair for Functional Materials in Medicine and Dentistry at the institute of Functional Materials and Bio-fabrication & Bavarian Polymer Institute, Uni-versity of Würzburg, Pleicherwall 2, 97070 Würzburg, Germany, [email protected]

Jürgen Groll, Chair for Functional Materials in Medicine and Dentistry at the institute of Functional Materials and Bio-fabrication & Bavarian Polymer Institute, Uni-versity of Würzburg, Pleicherwall 2, 97070 Würzburg, Germany, [email protected]

Introduction Supplement-free induction of macrophage polarization solely through the topography of materials is an auspicious strat-

egy but has so far significantly lacked behind the efficiency and intensity of media-supplementation based protocols.

Methods We investigated Melt-Electrowriting (MEW) for the fabrication of fibrous 3D scaffolds made from poly(ε-caprolactone)

(PCL) and advanced the precisely defined inter-fiber spacing from 100 µm down to 40 µm for a variety of pore geometries

(rectangular, triangular and round) with the aim to identify structural design criteria for the fabrication of scaffolds with

strong topographic immunomodulation for human monocyte-derived macrophages.

Results

These scaffolds did facilitate primary human macrophage differentiation towards the M2 type, which was most pro-

nounced for box-shaped pores with 40 µm inter-fiber spacing, but not with the desired efficiency.

We then found that human monocyte-derived macrophages show a strong M2a like pro-healing polarization when cul-

tured on type I rat-tail collagen fibers but not on collagen I films. Therefore, we hypothesized that highly aligned nano-

fibrils also of synthetic polymers, if packed into larger bundles in 3D topographical biomimetic similarity to native col-

lagen I fibers, would induce a localized macrophage polarization. Through integration of flow directed polymer phase

separation into MEW we developed Melt-Electrofibrillation, a process that yields nano-fiber bundles with a remarkable

structural similarity to native collagen I fibers, particularly for medical grade PCL. These biomimetic fibrillar structures

indeed induce a pronounced elongation of human monocyte-derived macrophages and unprecedentedly triggered their

M2-like polarization similar in efficacy as IL-4 cytokine treatment (M. Ryma et al: Translation of Collagen Ultrastructure

to Biomaterial Fabrication for Material-Independent but Highly Efficient Topographic Immunomodulation. Advanced

Materials 2021, https://doi.org/10.1002/adma.202101228).









https://doi.org/10.1002/adma.202101228

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Additive manufacturing of piezoelectric barium titanate