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Dissertation_Md Omar Faruk Emon.pdf (5.93 MB)

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Ionic Liquid–Based 3D Printed Soft Pressure Sensors and Their Applications

Emon, Md Omar Faruk
http://rave.ohiolink.edu/etdc/view?acc_num=akron1593542345792441

Abstract Details

2020, Doctor of Philosophy, University of Akron, Mechanical Engineering.
Soft and stretchable electronics will play an important role in the areas of robotics, prosthetics, wearables, and energy harvesting devices. The emergence of smart technologies is spurring the development of a wider range of applications for stretchable and conformable pressure sensors. Concomitant with the material research on soft sensors, the fabrication method is also gaining major progress. The manufacturing and design flexibility offered by additive manufacturing (AM) may enable the fabrication of sensors that are superior to those fabricated by conventional manufacturing techniques. AM could realize applications of the sensors which are difficult to achieve via a conventional method. In this work, a flexible and stretchable pressure sensor has been proposed. A pressure-sensitive membrane was fabricated through the polymerization of an ionic liquid (IL)-prepolymer blend. Stretchable conductive strips or electrodes were fabricated using a carbon nanotube (CNT)/polymer composite. The IL-based pressure-sensitive layer was sandwiched between CNT–based stretchable electrodes and encapsulated within stretchable top and bottom insulating layers. The multi-layer multi-material sensor was first fabricated through a screen-printing and molding process for evaluation and characterization purposes. Sensor performance was investigated for different degrees of crosslinking and polymerization, concentrations of IL, and thicknesses of the IL/polymer layer. The experimental results showed that these variables affect the sensitivity of the sensor. Next, various forces were applied to a screen-printed sensor to determine the reliability, sensitivity, and dynamic range. The proposed IL-based sensor displayed superior performance with high sensitivity and reliability. The sensor was also investigated for temperature dependence and shelf life. Different applications of the screen-printed sensor were explored such as sensor embedded tire and sensor embedded insole. While the sensors for these experiments were manufactured using screen printing and molding processes, the materials used for sensor fabrication are 3D printable, as 3D printing is the target manufacturing technique. A multi-material 3D printing system with three extrusion heads was developed to fabricate the soft pressure sensor. The system employs an extrusion-based direct-print (DP) process. The capability of the system was demonstrated by printing structures made from three materials. The sensor materials were modified for the extrusion-based printing and printing parameters were identified for different materials of the sensor. Next, a flat sensor was 3D printed via a planar 3D printing technique. The 3D printed sensor was evaluated for different loading conditions. Finally, a sensor was conformally 3D printed on a free-form fingertip. The non-flat sensor model was conformally sliced to generate the curvilinear toolpath for conformal printing. Sensors fabricated via molding/screen-printing, planar 3D printing, and conformal 3D printing were compared for their responses. A 3D printed sensor application was explored by developing a grasping aid for neuropathy patients. Introducing IL to fabricate a soft pressure sensor opens newer possibilities for research and applications in the area of stretchable electronics. AM provides a unique freedom for design customization. Soft sensor produced via AM is believed to usher numerous novel studies in the future.
Jae-Won Choi, PhD (Advisor)
Gregory Morscher, PhD (Committee Member)
Siamak Farhad, PhD (Committee Member)
Kye-Shin Lee, PhD (Committee Member)
Thein Kyu, PhD (Committee Member)
146 p.
Mechanical Engineering
3D Printing; ionic liquid; additive manufacturing; pressure sensor; soft polymer; polymer blend; soft electronics; stretchable electronics

Recommended Citations

Citations

  • Emon, M. O. F. (2020). Ionic Liquid–Based 3D Printed Soft Pressure Sensors and Their Applications [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1593542345792441

    APA Style (7th edition)

  • Emon, Md Omar Faruk. Ionic Liquid–Based 3D Printed Soft Pressure Sensors and Their Applications. 2020. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1593542345792441.

    MLA Style (8th edition)

  • Emon, Md Omar Faruk. "Ionic Liquid–Based 3D Printed Soft Pressure Sensors and Their Applications." Doctoral dissertation, University of Akron, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1593542345792441

    Chicago Manual of Style (17th edition)

akron1593542345792441
151
© 2020, all rights reserved.
This open access ETD is published by University of Akron and OhioLINK.