PhD Dissertation | Strategies for tuning sensitivity to strain in sensors for flexible electronics | Yangyang Xin

09 December, 2021

PRESENTER: Yangyang Xin, Ph.D. Candidate Supervised by Prof. Gilles. Lubineau
DATE: Wednesday, December 15, 2021
TIME:  3:00 pm - 5:00 pm
LOCATION: Building 4, Level 5, Room# 5209
Zoom link to join the event:

Significant developments in flexible/stretchable electronics are needed due to the increasing sensing demand in soft robotics, prostheses, and human-machine interfaces. Stretchable strain sensors must be extremely sensitive to the applied strain in order to be used in monitoring human movement, tracking pulses, and identifying sounds. Percolated networks based on nanomaterials with intrinsic stretchability are primarily used to create large stretchable strain sensors with high sensitivity and stretchability. However, sensitivity and stretchability are two opposite faces of a coin. While stretchable, these sensors face limited sensitivity both in tension and compression. The aforementioned drawbacks limit application such as large-scale deformable surface monitoring and effective e-skins for monitoring complex strain states. Pollution from strain, on the other hand, is a problem that must be avoided for other types of stretchable sensors. Strain-insensitive sensors are mostly based on special geometrical design of the sensing area with a complicated fabrication. New methods for developing strain-insensitive sensors based on percolated networks are urgently needed to simplify the fabrication process.

We are introducing here new techniques to  enable new generations of sensors with a complete control of their sensitivity to strain from zero gauge factor to ultra-high gauge factor depending on the pursued applications. The central idea is to control the piezo-resistivity by a very fine control of the microstructure, especially by the well-design introduction of cracks. These cracks, as well as other mechanisms of degradation accompanying these cracks, results in ultra-high piezoresistive response. When unsensitivity to strain is needed, out strategy relies on leveraging the properties of the Seebeck effect in networks of nanoparticles. We demonstrate and explain how Seebeck-based sensors can be used to get fully strain independent measurements of other physical quantities.

Yangyang. Xin is a Ph.D. candidate in Mechanics of Composites for Energy and Mobility Lab lead by Prof. Gilles. Lubineau. He joined MCEM, physical sciences and engineering division (PSE), Mechanical Engineering Program, KAUST, in January 2017. He got his Bachelor in Reliability engineering from Harbin Engineering University, and in Control Engineering from Beihang University in people republic of China. His research has been focus on the design of stretchable electronic applied in artificial skin, soft robotic, and human-machine interface.