The purpose of this lab was to investigate the printability of cellulose nanofiber/carbon nanotubes, their functions as actuators, and to compare these properties with MXene/nano cellulose gels. Data on MXene/nano cellulose gel was obtained from previous research made by Hamedi labs. Data on carbon nanotubes were collected through experiments evaluating different concentrations and sonication times to yield a gel with high conductivity and viscosity. While it was concluded that both gels could be printed into 2D or 3D shapes, the latter failed to maintain its structure over time due to issues with drying. However, it was found that only 2D MXene/CNF could be used as a reversible actuator. / Syftet med laborationen var att undersöka 3D skrivningsförmågan för nanocellulosa/ kolnanorör samt samt deras förmåga att fungera att svälla elektroniskt. Vidare jämfördes dessa egenskaper med MXene/nanocellulosageler. Data på MXene/nanocellulosa insamlades från tidigare experiment gjorda av Hamedi labs. Data på kolnanorör insamlades genom en rad experiment, vilka utvärderade olika koncentrationer och sonikeringstider för att producera geler med hög konduktivitet och viskositet. Slutsatsen blev att båda gelerna kunde 3D printas, men endast MXene/nanocellulosageler kunde användas för elektronisk svällning och avsvällning. Inga geler kunde göras till 3D strukturer.

This work presents the development of 3D printed microfluidic devices and their application to microchip analysis. Initial work was focused on the development of the printer resin as well as the development of the general rules for resolution that can be achieved with stereolithographic 3D printing. The next stage of this work involved the characterization of the printer with a variety of interior and exterior resolution features. I found that the minimum positive and negative feature sizes were about 20 μm in either case. Additionally, micropillar arrays were printed with pillar diameters as small as 16 μm. To demonstrate one possible application of these small resolution features I created microfluidic bead traps capable of capturing 25 μm polystyrene particles as a step toward capturing cells. A second application which I pioneered was the creation of devices for microchip electrophoresis. I separated 3 preterm birth biomarkers with good resolution (2.1) and efficiency (3600 plates), comparable to what has been achieved in conventionally fabricated devices. Lastly, I have applied some of the unique capabilities of our 3D printer to a variety of other device applications through collaborative projects. I have created microchips with a natural masking monolith polymerization window, spiral electrodes for capacitively coupled contactless conductivity detection, and a removable electrode insert chip. This work demonstrates the ability to 3D print microfluidic structures and their application to a variety of analyses.

3D-printing is a new and upcoming manufacturing technique that can significantly reduce time and material losses in production. Fused deposition modeling (FDM) is one of the most commonly used 3D-printing methods for processing conventional thermoplastic polymers. To reduce the printing time and usage of material via FDM technology, a user typically specifies infill density. Therefore, it is important to understand how this printing parameter affects the fire and mechanical properties of the 3D-printed object.  This study aims to investigate the effect of various infill densities on mechanical and fire properties of polylactic acid (PLA) composites produced by FDM 3D-printing technology. PLA composites of five different infill densities were 3D-printed: 20%, 40%, 60%, 80% and 100%. The samples for all tests were designed in AutoCAD and then imported into the slicing software, Ultimaker Cura. The 3D-printer used for printing was the Ultimaker S3 which uses FDM technology. To test the fire and mechanical behavior of 3D-printed PLA composites three tests were conducted: cone calorimeter test, tensile test and UL-94 flammability test. The cone calorimeter testing was done using the incident radiation of 35 kW/m2. The results showed that the trend of HHR curves of all infill densities are akin to each other, though the peak heat release rate and total heat released increases with higher infill density. Time to ignition was also longer for samples with higher infill density. Tensile testing was conducted according to the ASTM D638 standard. The results showed that with increasing infill density mechanical properties improved, with 100% infill density having the highest tensile strength (58.15 MPa) and elastic modulus (1472.1 MPa). From the UL-94 test results no difference in flammability could be observed. Every sample had no rating, which implies that PLA specimens of all infill densities are very flammable, with long afterflame and heavy flammable dripping. The study concludes that among the examined infill densities, no ideal percentage of infill density could be found. Requirements based on application will determine what infill density is most appropriate. Nevertheless, the data collected can hopefully provide a useful reference in designing and manufacturing 3D-printed PLA composites.

No description available.

No description available.

Background Brain biopsy of intracranial lesions is often necessary to determine specific therapy. The cost of the currently used stereotactic rigid frame and optical tracking systems for brain biopsy in dogs is often prohibitive or accuracy is not sufficient for all types of lesion. Objectives To evaluate the application accuracy of an inexpensive magnetic resonance imaging-based personalized, 3D printed brain biopsy device. Animals Twenty-two dog heads from cadavers were separated into 2 groups according to body weight (<15 kg, >20 kg). Methods Experimental study. Two target points in each cadaver head were used (target point 1: caudate nucleus, target point 2: piriform lobe). Comparison between groups was performed using the independent Student's t test or the nonparametric Mann-Whitney U Test. Results The total median target point deviation was 0.83 mm (range 0.09-2.76 mm). The separate median target point deviations for target points 1 and 2 in all dogs were 0.57 mm (range: 0.09-1.25 mm) and 0.85 mm (range: 0.14-2.76 mm), respectively. Conclusion and Clinical Importance This magnetic resonance imaging-based 3D printed stereotactic brain biopsy device achieved an application accuracy that was better than the accuracy of most brain biopsy systems that are currently used in veterinary medicine. The device can be applied to every size and shape of skull and allows precise positioning of brain biopsy needles in dogs.

The reliance on low-viscosity and photoactive resins limits the accessible properties for vat photopolymerization (VP) materials required for engineering applications. This has limited the adoption of VP for producing end-use parts, which typically require high MW polymers and/or more stable chemical functionality. Decoupling the viscosity and molecular weight relationship for VP resins has been completed recently for polyimides and highperformance elastomers by photocuring a scaffold around polymer precursors or polymer nanoparticles, respectively. Both of these materials are first shaped by printing a green part followed by thermal post-processing to achieve the final part properties. This dissertation focuses on improving the processability of these material systems by (i) investigating the impact of scaffold architecture and polysalt monomer composition on photocuring, thermal post-processing, and resulting thermomechanical properties and (ii) developing a Monte Carlo ray-tracing (MCRT) simulation to predict light scattering and photocuring behavior in particle-filled resins, specifically zinc oxide nanoparticles in a rigid polyester resin and styrene butadiene rubber latex resin. The first portion of the dissertation introduces VP of a tetra-acid and half-ester-based polysalt resin derived from 4,4'-oxydiphthalic anhydride and 4,4-oxydianiline (ODPA-ODA), a fully aromatic polyimide with high glass transition temperature and thermal stability. This polyimide, and polyimides like this, find use in demanding industries such as aerospace, automotive and electronic applications. The author evaluated the hypothesis that a non-bound triethylene glycol dimethacrylate (TEGDMA) scaffold would facilitate more efficient scaffold burnout and thus achieve parts with reduced off-gassing potential at elevated temperatures. Both resins demonstrated photocuring and were able to print solid and complex latticed parts. When thermally processed to 400 oC, only 3% of the TEGDMA scaffold remained within the final parts. The half-ester resin exhibits higher char yield, resulting from partial degradation of the polyimide backbone, potentially caused by lack of solvent retention limiting the imidization conversion. The tetra-acid exhibits a Tg of 260oC, while the half-ester displays a higher Tg of 380 oC caused by the degradation of the polymer backbone, forming residual char, restricting chain mobility. Solid parts displayed a phase-separated morphology while the half-ester latticed parts appear solid, indicating solvent removal occurs faster in the half-ester composition, presumably due to reduced polar acid functionality. This platform and scaffold architecture enables a modular approach to produce novel and easily customizable UV-curable polyimides to easily increase the variety of polyimides and the accessible properties of printed polyimides through VP. The second section of this dissertation describes the creation and validation of a MCRT simulation to predict light scattering and the resulting photocured shape of a ZnO-filled resin nanocomposite. Relative to prior MCRT simulations in the literature, this approach requires only simple, easily acquired inputs gathered from dynamic light scattering, refractometry, UV-vis spectroscopy, beam profilometry, and VP working curves to produce 2D exposure distributions. The concentration of 20 nm ZnO varied from 1 to 5 vol% and was exposed to a 7X7 pixel square ( 250 µm) from 5 to 11 s. Compared to experimentally produced cure profiles, the MCRT simulation is shown to predict cure depth within 10% (15 µm) and cure widths within 30% (20 µm), below the controllable resolution of the printer. Despite this success, this study was limited to small particles and low loadings to avoid polycrystalline particles and maintain dispersion stability for the duration of the experiments. Expanding the MCRT simulation to latex-based resins which are comprised of polymer nanoparticles that are amorphous, homogeneous, and colloidally stable. This allows for validating the MCRT with larger particles (100 nm) at higher loadings. Simulated cure profiles of styrene-butadiene rubber (SBR) loadings from 5 vol% to 25 vol% predicted cure depths within 20% ( µm) and cure widths within 50% ( µm) of experimental values. The error observed within the latex-based resin is significantly higher than in the ZnO resin and potentially caused by the green part shrinking due to evaporation of the resin's water, which leads to errors when trying to experimentally measure the cure profiles. This dissertation demonstrates the development of novel and functional materials and creation process-related improvements. Specifically, this dissertation presents a materials platform for the future development of unique photocurable engineering polymers and a corresponding physics-based model to aid in processing. / Doctor of Philosophy / Vat Photopolymerization (VP) is a 3D printing process that uses ultraviolet (UV) light to selectively cure liquid photosensitive resin into a solid part in a layer-by-layer fashion. Parts produced with VP exhibit a smooth surface finish and fine features of less than 100 µm (i.e., width of human hair). Recoating the liquid resin for each layer limits VP to low-viscosity resins, thus limiting the molecular weight (and thus performance) of the printed polymers accessible. Materials that are low molecular weight are limited in achieving desirable properties, such as elongation, strength, and heat resistance. Solvent-based resins, such as polysalt and latex resins have demonstrated the ability to decouple the viscosity and molecular weight relationship by eliminating polymer entanglements using low-molecular-weight precursors or isolating high-molecular-weight polymers into particles. This dissertation focuses on expanding and improving the printability of these methods. The second chapter of the dissertation investigates the impact of scaffold architecture in printing polyimide polysalts to improve scaffold burnout. Polysalts are polymers that exist as dissolved salts in solution, with each monomer holding two electronic charges. When heated, the solvent evaporates and the monomers react to form a high molecular-weight polymer. While previous work featured a polysalt that was covalently bonded to the monomers, the polysalt in this work is made printable by co-dissolving a scaffold. The polysalt resins are photocured and thermally processed to polymerize and imidize into a high-molecular-weight polymer, while simultaneously pyrolyzing the scaffold. Using a co-dissolved scaffold allows the investigation of two different monomers of tetra-acid and half-ester functionality. The half-ester composition underwent degradation during heating, increasing the printed parts' glass transition or softening point. The scaffold had little impact on the polysalt polymerization or final part properties and was efficiently removed, with only 3% remaining in final parts. The composition and properties of the monomers selected played a bigger role due to partial degradation altering the properties of the final parts. Overall, this platform and scaffold architecture allows for a larger number of polyimides to be accessible and easily customizable for future VP demands. The third chapter describes the challenges of processing photocurable resins that contain particles due to the UV light scattering in the resin vat during printing. When the light from the printer hits a particle, it is scattered in all directions causing the layer shape to be distorted from the designed shape. To overcome this, a Monte Carlo ray-tracing (MCRT) simulation was developed to mimic light rays scattering within the resin vat. The simulation was validated by comparing simulation results against experiment trials of photocuring resins containing 20nm zinc oxide (ZnO) nanoparticles. The MCRT simulation predicted all the experimental cure depths within 10% (20 µm) and cured widths within 30% (15 µm) error. Despite the high accuracy, this study was limited to small particles and low concentrations. Simulating larger particles is difficult as the simulation assumes each particle to be uniform throughout its volume, which is atypical of large ceramic particles. The fourth chapter enables high particle volume loading by using a highly stretchable styrene-butadiene rubber (SBR) latex-based resin. Latex-based resins maintain low viscosity by separating large polymer chains into nano-particles that are noncrystalline and uniform. When the chains are separated, they cannot interact or entangle, keeping the viscosity low even at high concentrations (>30 vol%). Like the ZnO-filled resin, the latex resin is experimentally cured and the MCRT simulation predicts the resulting cure shape. The MCRT simulation predicted cure depths within 20% (100 µm) and over-cure widths within 50% (100 µm) of experimental values. This error is substantially higher than the ZnO work and is believed to be caused by the water evaporating from the cured resin resulting in inconsistent measurements of the cured dimensions.

The Automated Design and Manufacturing Laboratory (ADML) is an automated assembly line located in the Engineering Product and Innovation Center (EPIC) that serves as the lab component for the course ME345: Automation and Manufacturing Methods. Over the semester the students learn how to program each automated component of the system, including Computer Numerically Controlled (CNC) mills, Universal Robot's 6 axis robotic arm, cameras, and Programmable Logic Controllers (PLC). Students then learn how to integrate each component together to develop a completely automated manufacturing process using an in-house manufacturing execution software. This integrated system is then used by the students to automatically manufacture new products of their own design that provide a societal benefit. Since 2019 multiple undergraduate students have worked on augmenting the ADML's capability with printing electronics by implementing Direct Ink Writing (DIW) based 3D printing and vacuum based pick and place into the ADML's assembly robot. Using these new capabilities, students in the ME345 will be able to design and manufacture electronic circuits. Moreover, a graduate level course will be developed based on this new addition to the ADML. The aim of this Thesis is to continue the work of previous students by finalizing the hardware and software necessary for the pick and place of electronic components and developing a conductive ink for electrical wiring and interconnects. A three component ink comprised of silver flake and a copolymer solution of acrylates/polytrimethylsiloxymethacrylate in a isododecane solvent was developed. This ink is biocompatible so it can be used by students without any hazard concern. It also exhibits a high degree of adhesion to the high-density polyethylene (HDPE) stock parts currently used in the ADML to ensure strong bonding to the electrical components. The mixing process, ink ingredient concentrations, and print parameters (i.e., extrusion pressure, print speed, and nozzle standoff distance) were optimized for compatibility with DIW based 3D printing, consistent and clog-free extrusion throughout the printing process, print fidelity, and a high electrical conductivity within approximately 1-2 orders of magnitude of bulk silver. / 2025-05-24T00:00:00Z

Intra-Body Communication (IBC) is a prospective technology where human tissue may be used as a signal medium in order to transmit useful data within the human body. Proposed applica- tions of this technology are prosthetics control or implanted device communication, potentially by establishing an Intra-Body Area Network (IBAN), which could further be enhanced by other IoT applications and 5G radio systems. Previous research at Uppsala University has shown the fat tissue to be a promising medium due to its low permittivity and loss tangent. This form of implementation is named Fat-IBC. This thesis aimed to produce a Fat-IBC enabled device, as a proof of concept. This project successfully produced and characterized phantom tissue, produced a basic demonstrator device in the form of a 3D-printed arm prosthetic, and integrated a wireless communication system into the arm prosthetic. The communication system was implemented using Arduino microcontrollers and XBee RF modules, based on the 802.15.4-based ZigBee protocol at 2.45 GHz. Muscle, fat, and skin phantom tissues were produced, with the muscle tissue being similar to other comparable tissue samples, while the fat and skin tissues deviated from such samples. A signal loss transmission test measured a -67 dB loss over 20 cm of fat tissue. Several potential issues with production and measurement were discussed. The arm demonstrator device was also tested by transmitting the control signal across phantom fat tissue, being fully functional through 10cm of tissue, and of limited function across 20cm of tissue.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第24849号 / 工博第5166号 / 新制||工||1987(附属図書館) / 京都大学大学院工学研究科機械理工学専攻 / (主査)教授 泉井, 一浩, 教授 松原, 厚, 教授 平山, 朋子 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM