Overview: A newly developed “e-tattoo” monitors electrodermal activity and reveals when a person is experiencing elevated stress levels. The “tattoo” attaches to the user’s palm and connects to a smartwatch.
Source: UT Austin
Our palms tell us a lot about our emotional state, they tend to get wet when people are excited or nervous. This response is used to measure emotional stress and help people with mental health issues, but the devices to do it now are bulky, unreliable and can perpetuate social stigma by sticking highly visible sensors to prominent parts of the body.
Researchers at the University of Texas at Austin and Texas A&M University have applied emerging electronic tattoo technology (e-tattoo) to this type of monitoring, known as electrodermal activity or EDA sensing.
In a new article recently published in Nature communicationthe researchers created a graphene-based e-tattoo that adheres to the palm, is nearly invisible and connects to a smartwatch.
“It’s so unobstructed that sometimes people forget they’re wearing it, and it also reduces the social stigma of wearing these devices in such prominent places on the body,” said Nanshu Lu, a professor in the Department of Aerospace Engineering and Engineering. Mechanics and leader of the project.
Lu and her staff have been developing wearable e-tattoo technology for many years. Graphene has been a favorite material because of how thin it is and how well it measures the electrical potential of the human body, leading to very accurate measurements.
But such ultra-thin materials cannot withstand much, if any, load. So that makes it challenging to apply them to areas of the body that move a lot, such as the palm/wrist.
The secret sauce of this discovery is how the e-tattoo on the palm can successfully transfer data to a rigid circuit — in this case, a commercially available smartwatch, in out-of-lab, ambulatory environments. They used a serpentine ribbon with two layers of graphene and gold that partially overlapped each other.
Swinging the ribbon back and forth allows it to handle the tension associated with hand movements for everyday activities such as holding the steering wheel while driving, opening doors, running, etc.
Current palm monitoring technology uses bulky electrodes that fall off and are highly visible, or EDA sensors that are applied to other parts of the body, giving a less accurate reading.
Other researchers have tried similar methods using straight, nanometer-thick ribbons to connect the tattoo to a reader, but they couldn’t handle the strain of constant movement.
Lu said the researchers for this study were inspired by virtual reality (VR), gaming and the inbound metaverse. VR is used in some cases to treat mental illness; however, the human-aware ability in VR remains lacking in many ways.
“You want to know if people are responding to this treatment,” Lu said. “Did it help them? It’s hard to say at the moment.”
About this neurotech research news
Author: Press Office
Source: UT Austin
Contact: Press Service – UT Austin
Image: The image is credited to UT Austin
Original research: Open access.
“Graphene e-tattoos for unobstructed palmar ambulatory electrodermal activity sensing enabled by heterogeneous tortuous ribbons” by Hongwoo Jang et al. Nature communication
Graphene e-tattoos for unobstructed palmar ambulatory electrodermal activity sensing enabled by heterogeneous serpentine ribbons
Electrodermal activity (EDA) is a popular index of mental stress. State-of-the-art EDA sensors suffer from palm obstruction or low palm signal fidelity. Our previous invention of sub-micron thin imperceptible graphene e-tattoos (GET) is ideal for unobstructed EDA sensing on the palm.
However, a robust electrical connection between ultra-thin devices and rigid circuit boards has been a long-missing component for ambulatory use.
To minimize the known stress concentration at their interfaces, we propose heterogeneous serpentine ribbons (HSPR), which refer to a GET serpentine partially overlapping a gold serpentine with no added glue.
A fifty-fold reduction in stretch in HSPR versus heterogeneous straight ribbons (HSTR) has been discovered and understood. The combination of HSPR and a soft interlayer between the GET and an EDA wristband enabled ambulatory EDA monitoring on the palm in free-living conditions.
A newly developed EDA event selection policy that uses an unbiased selection of staged events validated our GET EDA sensor against gold standards.