Design and fabrication of soft sensors with conductive thermoplastic polyurethane
Flexible Sensors are soft electronic devices that can detect and perceive external signals from physical stimuli like force, strain, and heat to chemical stimuli like organic compounds and ions. They are utilized everywhere in our modern daily lives, from wearable devices and environmental mon...
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| Format: | Thesis-Master by Coursework |
| Language: | English |
| Published: |
Nanyang Technological University
2024
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| Online Access: | https://hdl.handle.net/10356/176053 |
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| Institution: | Nanyang Technological University |
| Language: | English |
| Summary: | Flexible Sensors are soft electronic devices that can detect and perceive external signals from
physical stimuli like force, strain, and heat to chemical stimuli like organic compounds and ions.
They are utilized everywhere in our modern daily lives, from wearable devices and
environmental monitoring to industrial applications; and the demand is still rising. A significant
trend is also witnessed in the conventional rigid solid-state sensing systems based on silicon
PCBs are now replaced by soft, flexible, stretchable, and lightweight systems, especially in
the abovementioned fields. However, further investigation of the working mechanisms of some
of these soft sensors is required as they can be quite different from that of the conventional
solid-state sensors, resulting in distinctive features in their sensing capability, such as the
negative piezoresistive effect of FFF-made piezoresistive soft sensors.
This report presents the design and development of a novel soft piezoresistive sensor fabricated
by the Fused Filament Fabrication (FFF) process with insulating and conductive TPU. The
research aims to develop a piezoresistive force sensor with conductive thermoplastic
polyurethane which can be fabricated in a single process by multi-material FFF process. These
sensor will be applied on an existing type of gripper developed earlier by Goh et al. The
sensor is designed to be flexible, lightweight, sensitive to the application of force, and can fit
with the structural design of the gripper. A series of controlled variable tests on different
periodic patterns, cross-sectional structure designs, and printing parameters are conducted to
optimize the sensor’s sensitivity under the application of compressive force. The application
of the sensor to be directly fabricated onto the soft gripper’s fingertip will be tested. This project 8
also focuses on investigating the piezoresistive mechanism of the sensor, which is absent in
most research in the relevant field.
This project contributes to the field of soft robotics and 3D printed electronics by providing a
novel sensor design and a set of printing setups to optimize the performance of a piezoresistive
sensor available to be fabricated by the most commonly used additive manufacturing
technology FFF (fused filament fabrication) with a common, accessible, and cheap material
which is cTPU (conductive thermoplastic polyurethane).
An optimized sensor design is achieved, which can generate a drastic 42% drop in resistance
under an even force of 50N. When it is applied on the gripper’s surface, it is also observed that
a similar 42% drop in resistance is present on the directly fabricated sensor. With the integration
of the pre-existing soft gripper, this sensor can be deployed in the manufacturing industry
for applications such as handling fragile or slippery items or collaborating with human workers. |
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