Simón Montoya-Bedoya – simonmontoyabedoya@gmail.com
Bluesky: @simontoyabe.bsky.social
Instagram: @simontoyabe
Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas, 78712-1591, United States
Prof. Michael R. Haberman (Walker Department of Mechanical Engineering, The University of Texas at Austin)
Other contributors to the research:
Donal P. Finegan (National Laboratory of the Rockies, Golden, CO, US)
Hadi Khani (Texas Materials Institute, The University of Texas at Austin)
Ofodike Ezekoye (Walker Mechanical Engineering Department, The University of Texas at Austin)
Popular version of 2aPAb4 – Non-destructive ultrasonic monitoring of next-generation lithium-ion batteries
Presented at the 189th ASA Meeting
Read the abstract at https://eppro02.ativ.me/appinfo.php?page=Session&project=ASAASJ25&id=3977608&server=eppro02.ativ.me
–The research described in this Acoustics Lay Language Paper may not have yet been peer reviewed–
Have you noticed how heavily our current society depends on batteries? Batteries are used everywhere, from powering your phone to electrifying mobility, and energy storage to mitigate the intermittent nature of renewable energy sources like wind and sun. This increased demand for lithium-ion batteries (LIBs) has led to the exploration of new technologies with improved attributes such as safer operation or improved lifetime. For example, silicon solid-state batteries (Si-SSB) are promising because silicon as an anode material offers a higher specific capacity (~3500 mAh/g) than graphite (~300 mAh/g) used in conventional LIBs. They are also potentially safer to operate due to the use of a solid electrolyte rather than the flammable liquid electrolyte used in conventional LIBs.
However, Si-SSBs come with their own challenges associated with the avoidance of a liquid electrolyte, primarily the requirement to maintain reliable interfacial contact between all the solid layers for lithium-ion movement. Si-SSBs are therefore more brittle and more prone to contact loss and fracture.
Another challenge in studying the intricate mechanical changes that arise from the electrochemical processes in the battery is that we are “blind” to them, in other words, we cannot see inside batteries while they are operating. That’s why, just as a doctor uses ultrasound to monitor a beating heart, we can use ultrasonic waves to monitor batteries without opening them, as represented by the cartoon in Fig. 1. The key to understanding what changes within the batteries is having information about how the movement of lithium ions alters its mechanical properties. When lithium ions migrate during charging and discharging, they cause swelling, internal stresses, and sometimes fracture within the battery structure. These mechanical changes can significantly affect the propagation of ultrasonic waves through the material. This is specifically true for the silicon anode, where silicon forms alloys with the lithium ions, rather than the lithium ions becoming embedded in the molecular structure as occurs in conventional batteries. These electrochemical changes lead to large volumetric and mechanical changes. Thus, SSBs are a compelling technology to explore using ultrasound using ultrasonic signals observables, such as shifts in the time of flight (TOF) of the wave through the battery, or changes in how sound is absorbed or scattered. These “acoustic fingerprints” can potentially help us gain more insights into degradation in these next-generation (“next-gen”) batteries and therefore improve the technology for more widespread use in commercial products.
Figure 1. Analogy of the usage of ultrasonic waves for battery diagnostics, similar to how a doctor would use ultrasonics to monitor heart health. [Image generated with AI using Google NanoBanana Pro]
We aim to extend the use of ultrasonic testing methods for next-gen batteries and investigate opportunities and challenges associated with evaluating this new technology. In this work, we investigated both contact-based and immersion ultrasonic testing to monitor changes in the mechanical properties of Si-SSBs under cycle-induced aging.
In general, our experiments showed an overall stiffness reduction with aging as indicated by the increase in ultrasonic wave TOF (see Fig 2a). Further, we observed an overall reduction of transmitted energy with increased cycling. These two findings may be associated with the accumulation of damage at layer interfaces associated with the creation of solid-gas interfaces and/or debonding between layers. Finally, ultrasonic imaging using immersion testing provided information regarding the distribution and evolution of damage in space as these next-gen batteries are aged (see Fig 2b).
By refining these techniques to evaluate next-gen battery technologies, we will develop more sensitive methods to determine when something is wrong before it’s too late. In a world increasingly dependent on safe and reliable energy storage, the ability to “listen” to batteries might be precisely what we need to power the clean energy revolution.
Figure 2. Evolution of cell stiffness during aging. a) Stiffness of the SSB, normalized to its initial value, plotted against discharge capacity for both charged (blue) and discharged (red) states. With representative ultrasonic images from transmitted signals at two states of the SSB: b.1) pristine before cycling, and b.2) after 40 cycles of aging. We observed a significant reduction in transmission in the middle region of the SSB. Warmer colors indicate higher transmission, and dashed outlines mark the active cell region.
T. Douglas mast – doug.mast@uc.edu
Instagram: @baglamist
University of Cincinnati, Cincinnati, OH, 45224, United States
Popular version of 2aBAa7 – Measure for measure: Diffraction correction for consistent quantification of bubble-related acoustic emissions
Presented at the 188th ASA Meeting
Read the abstract at https://doi.org/10.1121/10.0037529
–The research described in this Acoustics Lay Language Paper may not have yet been peer reviewed–
Microscopic bubbles, when caused to vibrate by ultrasound waves, can be powerful enough to break through the body’s natural barriers and even to destroy tissue. Growth, resonance, and violent collapse of these microbubbles, called acoustic cavitation, is enabling new medical therapies such as drug delivery through the skin, opening of the blood-brain barrier, and destruction of tumors. However, the biomedical effects of cavitation are still challenging to understand and control. A special session at the 188th meeting of the Acoustical Society of America, titled “Double, Double, Toil and Trouble – Towards a Cavitation Dose,” is bringing together researchers working on methods to consistently and accurately measure these bubble effects.
For more than 30 years, scientists have measured bubble activity by listening with electronic sensors, called passive cavitation detection. The detected sounds can resemble sustained musical tones, from continuously vibrating bubbles, or applause-like noise, from groups of collapsing bubbles. However, results are challenging to compare between different measurement configurations and therapeutic applications. Researchers at the University of Cincinnati are proposing a method for reliably characterizing the activity of cavitating bubbles by quantifying their radiated sound.
A passive cavitation detector (left) listens for sound waves radiated by a collection of cavitating bubbles (blue dots) within a region of interest (blue rectangle).
The Cincinnati researchers are trying to improve measurements of bubble activity by precisely accounting for the spatial sensitivity patterns of passive cavitation detectors. The result is a measure of cavitation dose, equal to the total sound power radiated from bubbles per unit area or volume of the treated tissue. The hope this approach will enable better prediction and monitoring of medical therapies based on acoustic cavitation.
Figure 1: In an experiment simulating drug delivery through the skin (left), a treatment source projects an ultrasound beam onto animal skin. A passive cavitation detector (PCD) listens for sound radiated by bubbles at the skin surface, while the skin’s permeability is measured from its electrical resistance. Measured bubble activity is quantified using the sensitivity pattern of the PCD within the treated region (highlighted blue circle).
The researchers reported results from two experiments testing their methods for characterizing cavitation. In experiments testing ultrasound methods for drug delivery through the skin (Figure 1), they found that total power of subharmonic acoustic emissions (like musical tones indicating sustained vibrations of resonating bubbles) per unit skin surface area consistently increased when the skin became more permeable, quantifying the role of bubble activity in drug delivery. In a second experiment (Figure 2), the researchers quantified bubble activity during heating of animal liver tissue by ultrasound, simulating cancer therapies called thermal ablation. They found that increased bubble activity could indicate both faster tissue heating near the treatment source and reduced heating further from the source.
Figure 2: An ultrasound (US) array sonicates animal liver tissue with a high-intensity ultrasound beam, causing tissue heating (thermal ablation) as used for liver tumor treatments. Increased bubble activity was found to reduce the depth of treatment, while sometimes also increasing the area of ablated tissue near the tissue surface.
This approach to measuring bubble activity could help to establish standard cavitation doses for many different ultrasound therapy methods. Quantitative measurements of bubble activity could help confirm treatment success, such as drug delivery through the skin, or to guide thermal treatments by optimizing bubble activity to heat tumors more efficiently. Standard measures of cavitation dose should also help scientists more rapidly develop new medical therapies based on ultrasound-activated microbubbles.
Ehsan Vatankhah – e.vatankhah@utexas.edu
The University of Texas at Austin, Austin, TX, 78712, United States
Popular version of 1pSA8 – Magnetostrictive-based Jerk Sensor: experimental characterization and analytical estimation of sensitivity
Presented at the 188th ASA Meeting
Read the abstract at https://doi.org/10.1121/10.0037435
–The research described in this Acoustics Lay Language Paper may not have yet been peer reviewed–
Researchers at the University of Texas at Austin have developed and tested a new type of accelerometer-a device that measures motion-using a special material called Terfenol-D. This work explores how magnetostrictive materials, which change their magnetic properties when stressed, can be used to sense movement in a simple and reliable way.
How the Sensor Works
The sensor uses a rod of Terfenol-D, a material known for its strong magnetostrictive effect. When the rod is subjected to acceleration (movement), it experiences stress that changes its magnetic state. This change generates a small voltage in a coil wrapped around the rod, which can be measured as an electrical signal. The design uses permanent magnets to provide a steady magnetic field, ensuring the sensor responds in a predictable, linear way.
Key Features and Findings
- Sensitive to Jerk: Unlike most motion sensors that respond to acceleration or velocity, this sensor naturally responds to “jerk,” which is the rate of change of acceleration. This means its sensitivity increases with frequency up to its first resonance, making its performance in terms of signal to noise ratio to excel as frequency increases.
- Low Output Impedance: The sensor produces signals that can be easily transmitted over long cables without losing strength, unlike some traditional accelerometers that require extra electronics to preserve signal strength.
- No External Power Needed: The sensor generates its own signal from motion, so it does not require an active power supply for operation, making it suitable for remote or hard-to-reach locations. The design avoids complex parts, which could make it easier and less expensive to manufacture.
Testing and Performance
The team tested the sensor using two methods: vibrating it with a piezoelectric device and striking a plate with a specialized hammer. In both cases, the sensor’s output matched well with predictions from computer models and theoretical calculations. The sensor demonstrated a low noise floor (the smallest signal it can reliably detect), comparing favorably with commercial accelerometers.
Measurement setup using automatic modal hammer for vibrating the sensor.
Potential Applications
- Seismic and Underwater Sensing: The sensor’s design is promising for applications such as seismic monitoring or underwater acoustic sensing, where devices may need to operate for long periods without maintenance or external power.
- Large-Scale Sensor Networks: Its simplicity and self-powered operation make it a good candidate for use in networks of sensors spread over wide areas, such as for environmental monitoring.
Next Steps
The researchers plan to further develop this technology for underwater use, where measuring motion accurately is essential for applications like underwater navigation or monitoring ocean conditions.
Funding
This research was supported by the Office of Naval Research.
Contact
For more information, contact Ehsan Vatankhah at the Chandra Family Department of Electrical and Computer Engineering, University of Texas at Austin.
