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Ghelich, P.

Publications and source records attributed to Ghelich, P..

2 recordsLinked to original sources

Approximating Scaffold Printability Utilizing Computational Methods

Bioprinting facilitates the generation of complex, three-dimensional (3D), cell-based constructs for various applications. Although multiple bioprinting technologies have been developed, extrusion-based systems have become the dominant technology due to the diversity of materials (bioinks) that can be utilized, either individually or in combination. However, each bioink has unique material properties and extrusion characteristics that affect bioprinting utility, accuracy, and precision. Here, we have extended our previous work to achieve high precision (i.e., repeatability) across samples by optimizing bioink-specific printing parameters. Specifically, we hypothesized that an adaptive neuro-fuzzy inference system (ANFIS) could be used as a computational method to address the imprecision in 3D bioprinting test data and uncover the optimal printing parameters for a specific bioink that result in high accuracy and precision. To test this hypothesis, we have implemented an ANFIS model consisting of four inputs (bioink concentration, printing pressure, speed, and temperature) and a single output to quantify the precision (scaffold bioprinted linewidth range). We validate our use of the bioprinting precision index (BPI) with both standard and normalized printability factors. In total, our results indicate that computational methods are a cost-efficient measure to improve the precision and robustness of extrusion 3D bioprinting with gelatin-based bioinks.

bioengineering↗

Fabrication and Modeling of Recessed Traces for Silicon-Based Neural Microelectrodes

Chronically-implanted neural microelectrodes are powerful tools for neuroscience research and emerging clinical applications, but their usefulness is limited by their tendency to fail after months in vivo. One failure mode is the degradation of insulation materials that protect the conductive traces from the saline environment. Studies have shown that material degradation is accelerated by mechanical stresses, which tend to concentrate on raised topographies such as conducting traces. Therefore, to avoid raised topographies, we developed a fabrication technique that recesses (buries) the traces in dry-etched, self-aligned trenches. The depth of the trenches and the thickness of the traces are matched so that overlying insulation materials are flat, which, according to finite-element modeling, reduces stress concentrations in the insulation material. Here, we provide details on process optimization, modeling of intrinsic stress, and characterization using SEM, focused ion-beam cross sections, profilometry, and electrochemical impedance testing. The technique requires no extra masks, is easy to integrate with existing processes, and produces flatness within about 10 nm.

bioengineering↗