We have several Ph.D. positions available in our group (https://sites.usc.edu/zhaogroup/) in Aerospace and Mechanical Engineering and Biomedical Engineering at University of Southern California for Fall 2023. We are an interdesciplinary group with broad interests in flexible and stretchable sensors, experimental mechanics, advanced materials, and micro/nano manufacturing. Our focus areas include 3D soft electronics, brain-machine interfaces, unconventional micro/nano fabrication, and engineered surfaces/interfaces. Candidates interested in these areas are encouraged to submit applications to our Ph.D. program here: https://viterbigradadmission.usc.edu/doctoral/how-to-apply-phd/. The deadline to apply is Dec. 15th, 2022. Please feel free to contact Prof. Zhao (hangbozh@usc.edu) if you have any questions.

The Zhao Research Group at USC has a postdoc position starting in Summer or Fall 2022 in the area of mechanics and manufacturing of flexible electronic sensors. Candidates with experience in finite element simulation, material characterization, and sensor design and fabrication are encouraged to apply by sending a CV to Dr. Hangbo Zhao (hangbozh@usc.edu).

We have several Ph.D. positions available in our group (https://sites.usc.edu/zhaogroup/) in Aerospace and Mechanical Engineering at University of Southern California for Fall 2022. We are an interdesciplinary group with broad interests in experimental mechanics, advanced materials, and manufacturing. Our focus areas include 3D soft electronics, engineered surfaces/interfaces, and active/smart materials. Candidates interested in these areas are encouraged to submit applications to our Ph.D. program here: https://viterbigradadmission.usc.edu/doctoral/how-to-apply-phd/. The deadline to apply is Dec. 15th, 2021. Please feel free to contact Prof. Zhao (hangbozh@usc.edu) if you have any questions.

In this work published in PNAS (https://www.pnas.org/content/118/19/e2100077118), we present compliant 3D frameworks that incorporate microscale strain sensors for high-sensitivity measurements of contractile forces of engineered optogenetic muscle tissue rings, supported by quantitative simulations.

Abstract:

Tissue-on-chip systems represent promising platforms for monitoring and controlling tissue functions in vitro for various purposes in biomedical research. The two-dimensional (2D) layouts of these constructs constrain the types of interactions that can be studied and limit their relevance to three-dimensional (3D) tissues. The development of 3D electronic scaffolds and microphysiological devices with geometries and functions tailored to realistic 3D tissues has the potential to create important possibilities in advanced sensing and control. This study presents classes of compliant 3D frameworks that incorporate microscale strain sensors for high-sensitivity measurements of contractile forces of engineered optogenetic muscle tissue rings, supported by quantitative simulations. Compared with traditional approaches based on optical microscopy, these 3D mechanical frameworks and sensing systems can measure not only motions but also contractile forces with high accuracy and high temporal resolution. Results of active tension force measurements of engineered muscle rings under different stimulation conditions in long-term monitoring settings for over 5 wk and in response to various chemical and drug doses demonstrate the utility of such platforms in sensing and modulation of muscle and other tissues. Possibilities for applications range from drug screening and disease modeling to biohybrid robotic engineering.

In this work, we present concepts that allow controlled introduction of buckling and twisting deformations to the mechanically guided assembly of 3D mesostructures.

Abstract: Recently developed methods in mechanically guided assembly provide deterministic access to wide-ranging classes of complex, 3D structures in high-performance functional materials, with characteristic length scales that can range from nanometers to centimeters. These processes exploit stress relaxation in prestretched elastomeric platforms to affect transformation of 2D precursors into 3D shapes by in- and out-of-plane translational displacements. This paper introduces a scheme for introducing local twisting deformations into this process, thereby providing access to 3D mesostructures that have strong, local levels of chirality and other previously inaccessible geometrical features. Here, elastomeric assembly platforms segmented into interconnected, rotatable units generate in-plane torques imposed through bonding sites at engineered locations across the 2D precursors during the process of stress relaxation. Nearly 2 dozen examples illustrate the ideas through a diverse variety of 3D structures, including those with designs inspired by the ancient arts of origami/kirigami and with layouts that can morph into different shapes. A mechanically tunable, multilayered chiral 3D metamaterial configured for operation in the terahertz regime serves as an application example guided by finite-element analysis and electromagnetic modeling.

Link: https://www.pnas.org/content/116/27/13239