.png)
1 day ago
4
Parkinson’s disease can be difficult to diagnose, but one common symptom of the progressive neurodegenerative condition is small, frequent tremors in the hands.
Now, with an eye towards screening and early detection of the disease, researchers have developed what they call a diagnostic pen to detect those hand motions. The pen does not write in the traditional sense. Instead, a flexible magnetic tip and ferrofluid ink convert movement into fluctuations in their magnetic field, taking advantage of what is known as the magnetoelastic effect. The magnetic flux produces an electrical current in a conductive coil built into the barrel of the pen.
In a small pilot study, that electrical signal was used to train a convolutional neural network to accurately differentiate between the writing of patients with Parkinson’s disease and a healthy group. The diagnostic pen and human study were presented in Nature Chemical Engineering today.
“While the underlying sensing mechanisms are well established, the true strength of this work lies in how the authors have ingeniously integrated them into a functional device,” says Pradeep Sharma, an engineer at the University of Houston who studies soft magnetic materials similar to the one used in the tip of the new stylus; he was not involved in the current research.
Who Created the Diagnostic Pen?
Because the device is capable of detecting small, high-frequency movements, it’s a good fit for examining hand tremors, says Gary Chen,lead author of the study and a Ph.D. candidate at the University of California, Los Angeles. The authors are primarily based in the bioengineering research group led by Jun Chen (no relation), which has been investigating uses for the magnetoelastic effect for around five years.
“We view it as a very promising technology,” says Gary Chen, “but as we indicate in our paper, our current study has some shortcomings.” Chiefly,larger follow-up studies with a more diverse pool of subjects are necessary to answer questions about the device and its potential applications. In the pilot study, training data came from only two patients with Parkinson’s disease and ten healthy control participants, and validation added an additional four participants, including one with Parkinson’s.
In addition to validating early results, further research could also help determine if the pen is able to distinguish between Parkinson’s and other conditions with tremor symptoms, and whether it can identify different stages of the same disease. What’s more, the researchers want to study whether the subject’s native language or dominant handedness affect the results, which might be important for clinical applications.
How Does the Diagnostic Pen Work?
The new pen’s tip is made of small neodymium magnets mixed into Ecoflex, a brand of silicone rubber advertised for production of prosthetics and film props. The body contains a reservoir of ferrofluid “ink,” which is surrounded by a barrel with a built-in coil of conductive yarn.
As a user draws or writes with the stylus, deformations in the tip change the magnetic field, and movement of the ferrofluid makes the pen sensitive to acceleration both across a writing surface or in the air. Minute magnetic fluctuations produce a current in the coil, and changes to that current were analyzed rather than the on-paper results of experimental writing or drawing tasks, as is commonly done in today’s neurological assessments.
Participants were asked to perform several tasks, including drawing loops and writing letters. Normalized data was used to train several types of machine learning algorithms, and the best performing analysis came from a one-dimensional convolutional neural network, which reached over 96 percent accuracy in identifying subjects with Parkinson’s.
Current fluctuations in testing were sometimes less than a microampere, and the study version of the pen connected to a current amplifier with a cable. Eventually, the group would like to transfer data wirelessly from pen to computer or smartphone, says Chen.
Other Applications for Magnetoelastic Materials
Soft magnetic materials similar to that used for the tip of the pen, sometimes called magnetorheological elastomers, are being investigated for a variety of uses, including how their properties change when exposed to an external magnetic field. The Jun Chen research group has also looked at using magnetoelastic materials for neck-worn patches speech assistance and more general human-machine interfaces, among other applications.
Earlier this year, a study estimated that there are around 12 million people living with Parkinson’s disease globally, a number that will double by 2050.
Chen emphasizes the importance of larger scale studies for evaluating the usefulness of the pen. “Admitting that does not compromise the promise,” he says, “though it may take many years or decades to finally get it delivered.”
