3D Printing of Composite Organic Semiconductor Microdevices for Biosensors and Organic Bioelectronics



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Bioelectronic devices aim to alleviate symptoms or return function to patients suffering from neural disorders / injuries. Choice of functional material and employment of advanced fabrication techniques constitute key elements in ultimate success of these devices. As an alternative to traditional metallic platforms, organic electroactive materials have garnered tremendous attention in neural devices. Consequently, the emerging field of organic bioelectronics has sought to interface the organic-based devices with the soft and ion-dominated neural tissue. Organic semiconductor materials (OSs), i.e. conjugated polymers, have emerged as one of the ideal candidates for neural interfaces, owing to their biocompatibility, soft mechanical properties, and mixed electronic / ionic conductivity. This thesis is primarily focused on development of soft and conductive micron-scale platforms for applications in organic bioelectronics and biosensors. In the course of the projects, much attention has been devoted towards design of microelectronic devices, employing advanced fabrication techniques, and formulation of composite biomaterials based on two common OSs; poly(3,4-ethylenedioxythiophene) and polypyrrole. The theme of research projects falls into two main categories: 1. Soft and bioactive platforms for neural regeneration, and 2. 3D-printed conductive microelectronic devices for organic bioelectronics and biosensors. In the first category, we have developed a micro-patterning technique and have created various profiles of laminin gradients on surface of OS thin films, which can be potentially employed for neural regeneration. The second category deals with design, fabrication and characterization of 3D-printed microelectronic devices. First, we have explored 3D printing of soft, conductive, and bioactive microstructures via direct laser writing, also known as multi-photon polymerization lithography (MPL). We have formulated conductive photosensitive inks, and fabrication and characterization of microelectronic devices such as hybrid neural microelectrodes, bioactive microstructures and high-performance glucose biosensors have been successfully demonstrated. We also report on development of an in-house 3D printing technique for fabrication of OS microdevices based on in-situ electrochemical polymerization. Microelectronic devices, bioactive structures and glucose biosensors have been fabricated using this technique. Overall, we envision that these microelectronic devices and platforms pave the way towards development of next-generation neural interfaces for organic bioelectronics and biosensing applications.



Organic Semiconductors, Organic Bioelectronics and Biosensors


Portions of this document appear in: Dadras-Toussi, Omid, Milad Khorrami, Sheereen Majd, and Mohammad Reza Abidian. "Gradients of Surface-Bound Laminin on Conducting Polymer Films for Potential Nerve Regeneration." In 2021 10th International IEEE/EMBS Conference on Neural Engineering (NER), pp. 395-398. IEEE, 2021; and in: Dadras-Toussi, Omid, Milad Khorrami, and Mohammad Reza Abidian. "Femtosecond Laser 3D-printing of Conductive Microelectronics for Potential Biomedical Applications." In 2021 43rd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC), pp. 1197-1200. IEEE, 2021; and in: Dadras-Toussi, Omid, VijayKrishna Raghunathan, Sheereen Majd, and Mohammad Reza Abidian. "Direct Laser 3D Printing of Organic Semiconductor Microdevices for Bioelectronics and Biosensors." In 2022 44th Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC), pp. 1569-1572. IEEE, 2022; and in: Dadras‐Toussi, Omid, Milad Khorrami, Anto Sam Crosslee Louis Sam Titus, Sheereen Majd, Chandra Mohan, and Mohammad Reza Abidian. "Multiphoton Lithography of Organic Semiconductor Devices for 3D Printing of Flexible Electronic Circuits, Biosensors, and Bioelectronics." Advanced Materials 34, no. 30 (2022): 2200512.