Prototyping of Polymer based Microbioreactors: Micromachining by using Poly(Methyl Methacrylate) and Poly(Dimethylsiloxane) Polymer Materials

2013 ◽  
Vol 63 (1) ◽  
Author(s):  
Hazwan Halimoon ◽  
Muhd Nazrul Hisham Zainal Alam
Keyword(s):  
Methyl Methacrylate ◽  
High Precision ◽  
Computer Aided Design ◽  
Soft Lithography ◽  
Processing Time ◽  
Polymer Materials ◽  
Poly Methyl Methacrylate ◽  
Design Considerations ◽  
Computer Aided ◽  
Aided Design

Polymers have been widely accepted as materials for the fabrication of microbioreactor prototypes. In this work, microfabrication strategies namely the micromachining and casting (soft lithography) with the use poly(methyl methacrylate) (PMMA) and poly(dimethylsiloxane) (PDMS) polymers as substrates for fabrications were discussed in details. A step-by-step illustration (including examples on digital prototyping of the microbioreactor by using a computer-aided-design (CAD) software) for the above mentioned micromachining procedures, and discussions on the necessary design considerations were presented as well. In the work, we showed the simplicity of such machining procedures for the fabrication of microbioreactor prototypes. It was confirmed that through micromachining, microbioreactor prototypes can be fabricated by using poly(methyl methacrylate) (PMMA) and poly(dimethylsiloxane) (PDMS) polymers with high precision (down to one tenth of mm). It was also demonstrated that the processing time for the fabrication of the microbioreactor prototypes was in the order of few hours and maybe days for a complex reactor design. 

Design of Four-Bar-Mechanism Stability Using Over-Constraint

2016 ◽  
Author(s):  
Ahmad Alqasimi ◽  
Craig Lusk
Keyword(s):  
Potential Energy ◽  
Computer Aided Design ◽  
Main Idea ◽  
Spring Stiffness ◽  
Stable States ◽  
Stable Position ◽  
Design Considerations ◽  
Computer Aided ◽  
Aided Design ◽  
Energy Element

This paper presents a new concept and method to design mechanisms’ stability using over-constraint. The designs involve the use of parametric Computer-Aided Design (CAD) software to synthesize a mechanism’s geometry in order to achieve a design’s specific bistability requirements. This method ensures a stable position without the need of a hard-stop. There are two main initial design considerations that need to be met in this analysis. First, both (first and second) state of the mechanism should be chosen and should represent the mechanism’s desired stable positions. The first state is the position that the mechanism was manufactured or assembled at, whereas the second state is the position at which the mechanism is toggled to. The second consideration is the assumption that the magnitude of the joints’ torsional spring stiffness is small i.e. living hinges. The main idea is to attach a Potential Energy Element (PEE), such as a spring or a compliant link, to the four-bar mechanism such that it is unstretched in both stable positions and has to deform (stretch or compress) during the motion between stable states. This approach seems to allow the designer considerable freedom in amount of motion between stable states and in the amount of force required to toggle between stable states.

scholarly journals Evolution of design considerations in complex craniofacial reconstruction using patient-specific implants

2016 ◽  
Vol 231 (6) ◽  
pp. 509-524 ◽  
Author(s):  
Sean Peel ◽  
Satyajeet Bhatia ◽  
Dominic Eggbeer ◽  
Daniel S Morris ◽  
Caroline Hayhurst
Keyword(s):  
Additive Manufacturing ◽  
Case Studies ◽  
Computer Aided Design ◽  
Titanium Implants ◽  
Patient Specific ◽  
Patient Case ◽  
Computer Aided Manufacturing ◽  
Design Considerations ◽  
Computer Aided ◽  
Aided Design

Previously published evidence has established major clinical benefits from using computer-aided design, computer-aided manufacturing, and additive manufacturing to produce patient-specific devices. These include cutting guides, drilling guides, positioning guides, and implants. However, custom devices produced using these methods are still not in routine use, particularly by the UK National Health Service. Oft-cited reasons for this slow uptake include the following: a higher up-front cost than conventionally fabricated devices, material-choice uncertainty, and a lack of long-term follow-up due to their relatively recent introduction. This article identifies a further gap in current knowledge – that of design rules, or key specification considerations for complex computer-aided design/computer-aided manufacturing/additive manufacturing devices. This research begins to address the gap by combining a detailed review of the literature with first-hand experience of interdisciplinary collaboration on five craniofacial patient case studies. In each patient case, bony lesions in the orbito-temporal region were segmented, excised, and reconstructed in the virtual environment. Three cases translated these digital plans into theatre via polymer surgical guides. Four cases utilised additive manufacturing to fabricate titanium implants. One implant was machined from polyether ether ketone. From the literature, articles with relevant abstracts were analysed to extract design considerations. In all, 19 frequently recurring design considerations were extracted from previous publications. Nine new design considerations were extracted from the case studies – on the basis of subjective clinical evaluation. These were synthesised to produce a design considerations framework to assist clinicians with prescribing and design engineers with modelling. Promising avenues for further research are proposed.

scholarly journals Review on Computer-Aided Design and Manufacturing of Drug Delivery Scaffolds for Cell Guidance and Tissue Regeneration

2021 ◽  
Vol 9 ◽  
Author(s):  
Aurelio Salerno ◽  
Paolo A. Netti
Keyword(s):  
Drug Delivery ◽  
Cell Fate ◽  
Computer Aided Design ◽  
Soft Lithography ◽  
Porous Scaffold ◽  
Tissue Growth ◽  
Porous Scaffolds ◽  
Computer Aided ◽  
Aided Design ◽  
Am Processes

In the last decade, additive manufacturing (AM) processes have updated the fields of biomaterials science and drug delivery as they promise to realize bioengineered multifunctional devices and implantable tissue engineering (TE) scaffolds virtually designed by using computer-aided design (CAD) models. However, the current technological gap between virtual scaffold design and practical AM processes makes it still challenging to realize scaffolds capable of encoding all structural and cell regulatory functions of the native extracellular matrix (ECM) of health and diseased tissues. Indeed, engineering porous scaffolds capable of sequestering and presenting even a complex array of biochemical and biophysical signals in a time- and space-regulated manner, require advanced automated platforms suitable of processing simultaneously biomaterials, cells, and biomolecules at nanometric-size scale. The aim of this work was to review the recent scientific literature about AM fabrication of drug delivery scaffolds for TE. This review focused on bioactive molecule loading into three-dimensional (3D) porous scaffolds, and their release effects on cell fate and tissue growth. We reviewed CAD-based strategies, such as bioprinting, to achieve passive and stimuli-responsive drug delivery scaffolds for TE and cancer precision medicine. Finally, we describe the authors’ perspective regarding the next generation of CAD techniques and the advantages of AM, microfluidic, and soft lithography integration for enhancing 3D porous scaffold bioactivation toward functional bioengineered tissues and organs.

Fixtureless Sensor Standoff Control for High-Precision Dimensional Inspection of Freeform Parts

2006 ◽  
Vol 129 (1) ◽  
pp. 172-179 ◽  
Author(s):  
Vijay Srivatsan ◽  
Reuven Katz ◽  
Debasish Dutta
Keyword(s):  
Turbine Blade ◽  
High Precision ◽  
Computer Aided Design ◽  
Manufacturing Systems ◽  
Turbine Blades ◽  
Dimensional Inspection ◽  
Manual Intervention ◽  
Precision Inspection ◽  
Computer Aided ◽  
Aided Design

High-precision, noncontact dimensional inspection requires sensor standoff control due to the working range limitation posed by high-precision range sensors. Constant sensor standoff with the surface of the part is necessary to ensure accurate measurement. This paper presents a novel computer-aided design (CAD) independent approach to sensor standoff control called “fixtureless sensor standoff control (FSC),” which contrary to current methods does not require a fixture or manual intervention for registration. This approach to sensor standoff control will enable rapid, flexible, and high-precision inspection of freeform parts, thus catering to the needs of future manufacturing systems. In the FSC methodology, the sensor’s position for the next measurement is estimated based on immediate previous measurements. The method was implemented on a four-axis machine used to inspect turbine blades. Results from measurement of an example turbine blade showed the deviation from desired standoff to be significantly smaller than the working range of the sensor.

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