One of our main areas of interest is applications of non-imaging low-intensity- and low-frequency ultrasound acoustic devices for screening, diagnosis, assessment, and treatment of different complexities. We have performed thousands of simulations, have developed and built several prototypes of acoustic wearables, and tested their applications in screening and diagnosis of implant failure, and muscle monitoring. Of course, we are doing a lot more that we are not just ready to share but if you are interested to work in this area make sure to contact us!
In medical sciences whenever we talk about ultrasound systems the first thing that comes to mind is an ultrasound probe or ultrasound imaging. However, we dont always need to construct an image to create an understanding. If we could understand the signals regardless of creating an image that could help us get over the limitations of imaging systems. For example, to create an image we need to use very high frequencies in orders of MHz, but these high frequencies constrain us from penetrating cortical bone. And if we use lower frequencies the images will lack the required spatial resolution necessary for imaging. Another limitation of imaging systems is that in these systems we only analyze the reflected waves and dismiss the scattered and penetrated waves that could contain very valuable information. Therefore, scientist created a field called acoustic emission, which simply tries to listen to the vibrations from joints or implants. Acoustic emission has shown promise for detecting implant wear and instability however, there is significant limitations in acoustic emission. We basically should solve an inverse mathematical problem that from the received signals understands the causes. This is very difficult because for many cases there is not a unique solution.
This is why we developed a new generation of acoustic wearables. In our systems we apply low-frequency and low-intensity waves to the domain/body from one or multiple acoustic transducers and read the domain reaction to these waves using multiple other acoustic transducers at the domain/body surface.
Screening of mechanical defects in hip implants:
To prove this concept, we started with a large set of finite element numerical simulations in COMSOL. We developed a simplified circular model of cross section of a hip implant surrounded by bone marrow, compact bone, muscle, fat, and skin (figure below). We then applied different defects as water bubbles, or a thin layer of water at the interface of the implant and bone marrow to simulate partial loosening or cross section of a crack at the interface.
The figure below shows the simulated displacement fields for a healthy implant, cracked interface and partially loose implant. we could see that for frequencies larger than 200 kHz the signals could detect very small differences between healthy and fractures and loosened implants. This frequency is much smaller than the frequencies of imaging systems and at this frequency we should penetrate the compact bone.
We then developed a new way of visualizing our data and performed machine learning to understand the signals better. For the full description of the work please check our recent paper, Yazdkhasti et al, 2024.
Ongoing projects:
There are several projects that we are working on these days using our real-life prototypes such as muscle monitoring, assessment of tendon conditions, bone quality etc. even though we are not completely ready to share these projects if you are interested in working on this feel free to reach out or apply through our portal.