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Device Technologies and Biomedical Robotics

Device Technologies and Biomedical Robotics - Poster Session B

Poster J1 - Fabrication of a piezoelectric heart-on-chip platform

Thursday, October 24, 2024
2:45 PM - 3:45 PM EST
Location: Exhibit Hall E, F & G

Introduction:  Organ-on-chip devices are used to model the physiological effects of multiple cells and tissues, allowing for the testing of diseases and pharmaceuticals in vitro. This model, the co-cultured cardiomyocytes on chip (CoCo Chip), was designed with key features including piezoelectric-polydimethylsiloxane (pz-PDMS) that converts mechanical energy into electrical energy, co-culture capability, and multiplexing capability. Pz-PDMS was designed for use in cell-culture surface using poly(vinylidene fluoride-cotrifluoroethylene). These features would allow for quantitative contractility outputs, more physiologically relevant results, and multiple, simultaneous cultures. The goal of this research was to fabricate a medium sized chip using pz-PDMS and create a cell culture platform that can non-invasively quantify myocyte contractility over time. To create a functioning chip, thickness of pz-PDMS at various spin coater RPM, laser cutting depth of pz-PDMS at different wattage, sensitivity of the thin film pz-PDMS cantilevers, and stamping techniques for aligning cells on the cantilever were all investigated.

Materials and

Methods:  The chip was designed by thermally evaporating chromium and gold with photolithography patterning and wet etching to produce a gold electrode slide. The gold electrode slide was initially spin coated with a PNIPAM liftoff layer and spin coated again with 5% pz-PDMS. The slide was placed in a custom 3D printed well design sealed with PDMS. Deionized water was filled in the well topped with a clear glass slide. Laser-cutting testing was performed using glass slides spin coated twice with a thin layer of 5% pz-PDMS. The laser cutting process was assessed with the Omtech laser-cutter to investigate proper speed and power settings for lifted cantilevers on the pz-PDMS slide. Depth of the laser cut was analyzed using z-stack images from confocal microscopy via 1µm fluorescent beads. Pz-PDMS thickness for laser cutting was investigated by examining various spin coater RPM and analyzed with the Keyence machine. Sensitivity of 5% pz-PDMS glass slides with gold electrodes were examined by dropping a 0.3g pipette tip from 10mm above the surface of the thin film and measuring the voltage produced by each electrode. The voltage output was recorded using the NI ELVIS Data Logger program. Final sensitivity data was processed using a custom MATLAB code. A PDMS stamp was coated in fibronectin and stamped onto thin films of pz-PDMS and PDMS to test if microcontact printing could be performed. ImageJ was used to examine the differences in stamping between Pz-PDMS and PDMS.

Results, Conclusions, and Discussions: Preliminary data for Laser-Cutting tests have revealed that power settings greater than 4.1watts cuts through the 15µm Pz-PDMS thin film. Future results will analyze thicker samples and characterize the laser cutting depth at different watts. Preliminary sensitivity testing of the pz-PDMS on the differing gold electrodes shows significant difference between the sensitivity from differing gold electrode patterns. The electrodes showed a pattern of a higher voltage output the closer they were together and the larger their surface area. Further sensitivity tests are being performed. Fibronectin stamping tests experiments have been performed comparing stamped pz-PDMS coverslips with stamped PDMS coverslips. In conclusion, these experiments help characterize the potential pz-PDMS thin film efficacy in outputting a voltage when displaced on the micro level as well as analyze patterned fibronectin attachment for future cardiomyocyte contractility measurements.

Acknowledgements (Optional):  We would like to acknowledge National Science Foundation Grant: EWFD 2243953 for supporting this REU project.