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16 results on '"Azim, Nilab"'

1. Four-Dimensional Printing of Multi-Material Origami and Kirigami-Inspired Hydrogel Self-Folding Structures.

Author

Appavoo, Divambal, Azim, Nilab, Elshatoury, Maged, Antony, Dennis-Xavier, Rajaraman, Swaminathan, and Zhai, Lei

Subjects
*POLY(ISOPROPYLACRYLAMIDE), *THREE-dimensional printing, *STRUCTURAL design, *POLYETHYLENE glycol, *SIMULATION software
Abstract

Four-dimensional printing refers to a process through which a 3D printed object transforms from one structure into another through the influence of an external energy input. Self-folding structures have been extensively studied to advance 3D printing technology into 4D using stimuli-responsive polymers. Designing and applying self-folding structures requires an understanding of the material properties so that the structural designs can be tailored to the targeted applications. Poly(N-iso-propylacrylamide) (PNIPAM) was used as the thermo-responsive material in this study to 3D print hydrogel samples that can bend or fold with temperature changes. A double-layer printed structure, with PNIPAM as the self-folding layer and polyethylene glycol (PEG) as the supporting layer, provided the mechanical robustness and overall flexibility to accommodate geometric changes. The mechanical properties of the multi-material 3D printing were tested to confirm the contribution of the PEG support to the double-layer system. The desired folding of the structures, as a response to temperature changes, was obtained by adding kirigami-inspired cuts to the design. An excellent shape-shifting capability was obtained by tuning the design. The experimental observations were supported by COMSOL Multiphysics® software simulations, predicting the control over the folding of the double-layer systems. [ABSTRACT FROM AUTHOR]

Published
2024
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5. Fabrication and Characterization of 3D Microelectrode Arrays (3D MEAs) with "Edge-Wrapped" Metal Interconnects and 3D-Printed Assembly Rigs for Simultaneous Optical and Electrical Probing of Nerve-on-a-Chip® Constructs

Author

Didier, Charles M., primary, Rountree, Corey, additional, Orrico, Julia Freitas, additional, Kundu, Avra, additional, Azim, Nilab, additional, Nguyen, Hieu, additional, Pasha, Syed K., additional, McCoy, Laurie, additional, Curley, J. Lowry, additional, Moore, Michael J., additional, and Rajaraman, Swaminathan, additional

Published
2021
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14. Fabrication and Characterization of 3D Printed, 3D Microelectrode Arrays for Interfacing with a Peripheral Nerve-on-a-Chip

Author

Kundu, Avra, McCoy, Laurie, Azim, Nilab, Nguyen, Hieu, Didier, Charles M., Ausaf, Tariq, Sharma, Anup D., Curley, J. Lowry, Moore, Michael J., and Rajaraman, Swaminathan

Abstract

We present a nontraditional fabrication technique for the realization of three-dimensional (3D) microelectrode arrays (MEAs) capable of interfacing with 3D cellular networks in vitro. The technology uses cost-effective makerspace microfabrication techniquesto fabricate the 3D MEAs with 3D printed base structures with the metallization of the microtowers and conductive traces being performed by stencil mask evaporation techniques. A biocompatible lamination layer insulates the traces for realization of 3D microtower MEAs (250 μm base diameter, 400 μm height). The process has additionally been extended to realize smaller electrodes (30 μm × 30 μm) at a height of 400 μm atop the 3D microtower using laser micromachining of an additional silicon dioxide (SiO2) insulation layer. A 3D microengineered, nerve-on-a-chip in vitromodel for recording and stimulating electrical activity of dorsal root ganglion (DRG) cells has further been integrated with the 3D MEA. We have characterized the 3D electrodes for electrical, chemical, electrochemical, biological, and chip hydration stability performance metrics. A decrease in impedance from 1.8 kΩ to 670 Ω for the microtower electrodes and 55 to 39 kΩ for the 30 μm × 30 μm microelectrodes can be observed for an electrophysiologically relevant frequency of 1 kHz upon platinum electroless plating. Biocompatibility assays on the components of the system resulted in a large range (∼3%–70% live cells), depending on the components. Fourier-transform infrared (FTIR) spectra of the resin material start to reveal possible compositional clues for the resin, and the hydration stability is demonstrated in in-vitro-like conditions for 30 days. The fabricated 3D MEAs are rapidly produced with minimal usage of a cleanroom and are fully functional for electrical interrogation of the 3D organ-on-a-chip models for high-throughput of pharmaceutical screening and toxicity testing of compounds in vitro.

Published
2021
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16. Polymer-based and Functionalized 3D Microelectrode Array (MEA) Biosensors

Author

Azim, Nilab

Subjects
Chemistry, Polymer Chemistry
Abstract

Microphysiological systems are three-dimensional (3D) in vitro systems that recapitulate crucial biological aspects of cell heterogeneity and native tissue architecture by mimicking complex structures that are impossible in two-dimensional (2D) cell cultures. Microelectrode arrays (MEAs) are biosensors used to spatially and temporally monitor the activity of microphysiological systems by transducing cellular signals into electronic signals to provide quantitative data on the in vitro system. Conventional MEAs are typically planar in nature, however, 3D MEAs offer several advantages such as better simulation of an in vivo cellular environment and improved signal-to-noise ratio and cell-electrode coupling. MEA fabrication utilizing traditional cleanroom methods is rather extensive, expensive, and specialized, therefore this thesis presents a transition from 2D MEAs fabricated via the cleanroom approach to 3D MEAs fabricated via the makerspace approach utilizing polymers. The first study in the thesis discussed the fabrication and characterization of 2D MEA devices using cleanroom methods and investigated post-processing methods to address limitations that arise for planar devices. The next study introduced the makerspace approach, where benchtop techniques were used to successfully fabricate and characterize a fully functional 3D MEA. A subsequent study investigated another benchtop method to define an electrical insulation using a pour-spin method of polystyrene solution. However, there was a challenge of adhesion of the PS to the substrate, which was improved by both utilizing another type of printer and functionalizing these surfaces with polydopamine. In the final study of the thesis, a benchtop technique called electrospinning was used to define synthetic polymer-based nanofibers atop of the 3D MEAs to simulate extracellular matrices as well as demonstrate their potential as drug delivery systems. This thesis demonstrates the highly versatile nature of makerspace microfabrication utilizing polymers to allow for new processes that offer advanced functionalities when producing microdevices such as 3D MEAs interfacing with microphysiological systems.

Published
2021

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