Kirigami-Based Field’s Metal Platforms for Wearable Doppler Ultrasound Devices

Authors

• Aussia M. Stander, University of Nebraska-LincolnFollow

First Advisor

Eric J. Markvicka

Committee Members

Gregory R. Bashford, Ryan M. Pedrigi

Date of this Version

4-2026

Document Type

Thesis

Citation

A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Master of Science

Major: Mechanical Engineering and Applied Mechanics

Under the supervision of Professor Eric J. Markvicka

Lincoln, Nebraska, April 2026

Comments

Copyright 2026, Aussia M. Stander. Used by permission

Abstract

Aneurysmal subarachnoid hemorrhage affects thousands of people worldwide and places victims at risk of secondary vasospasm, which if untreated is often fatal. The Lindegaard ratio is a reliable clinical indicator of vasospasms calculated with blood velocity measurements from the medial cerebral artery and the ipsilateral internal carotid artery. Current measurement methods with conventional ultrasound devices are insufficient for monitoring patients. Trained technician availability is limited, so evaluations are performed intermittently (1-2 times per day), greatly increasing the risk of a vasospasm occurring undetected. Wearable ultrasound devices are a promising method for continuously monitoring the Lindegaard ratio, but existing devices are unsuitable for monitoring blood velocity in the ipsilateral internal carotid artery that runs parallel to the surface of the skin. In addition, patient anatomic variability makes it difficult to use devices with a fixed piezoelectric transducer orientation. Here, I introduce a reconfigurable wearable ultrasound device inspired by kirigami, the Japanese art of paper cutting, to transform 2D structures into 3D through the application of strain. Such structures can produce controllable and predictable geometric features through out-of-plane buckling to tune the orientation of a piezoelectric transducer for optimal Doppler angle alignment. Field’s metal, a low-temperature melt alloy, is patterned onto the kirigami substrate to maintain the transducer orientation in a stress-free state. When the device is strained, the Field’s metal plastically deforms at room temperature and can return to the zero-strain state through a simple heating procedure for reusability. The dynamic wearable device was evaluated using a phantom flow model at different strains to determine the effect of feature angle on velocity measurements. Doppler spectra and fast-time slow-time graphs found strong correlation between increasing feature angle and flow velocity, indicating this proof-of-concept device is a promising direction for creating a dynamic ultrasound patch for monitoring the Lindegaard ratio in at-risk patient populations.

Advisor: Eric J. Markvicka