Palm e-Tattoo can tell when you’re stressed
Summary: A newly developed “e-tattoo” monitors electrodermal activity, detecting when a person is experiencing elevated levels of stress. The “tattoo” is attached to the user’s palm and connected to a smart watch.
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 distress and help people with mental health problems, but the devices for doing so are now bulky, unreliable and can perpetuate social stigma by affixing highly visible sensors to prominent parts of the body.
Researchers from the University of Texas at Austin and Texas A&M University have applied new electronic tattoo (e-tattoo) technology to this type of tracking, known as electrodermal activity or EDA sensing.
In a new article published recently in Nature Communicationsresearchers have created a graphene-based e-tattoo that attaches to the palm of the hand, is nearly invisible, and connects to a smart watch.
“It’s so unobtrusive that people sometimes forget they’re wearing them, 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 project leader.
Lu and her collaborators have been advancing wearable e-tattoo technology for many years. Graphene has been a favored material because of its thinness and how well it measures the electrical potential of the human body, leading to very precise readings.
But such ultra-thin materials cannot handle much, if any, strain. So applying them to parts of the body that involve a lot of movement, such as the palm/wrist, is challenging.
The secret sauce of this discovery is how an e-tattoo on the palm can successfully transmit data to a rigid circuit – in this case a commercially available smartwatch, in an ambulatory setting outside of a laboratory. They used a serpentine ribbon that has two partially overlapping layers of graphene and gold.
By moving the strap back and forth, it can handle the strain that comes with arm movements for everyday activities like holding the steering wheel while driving, opening doors, running, etc.
Current palm tracking technology uses bulky electrodes that fall in and are highly visible, or EDA sensors applied to other parts of the body, which give a less accurate reading.
Other researchers tried similar methods using nanometer-thick rectilinear strips to connect the tattoo to the reader, but they couldn’t handle the strain of constant motion.
Lu said the researchers were inspired by virtual reality (VR), gaming and the upcoming metaverse for this research. VR is used in some cases to treat mental illness; however, the ability of human consciousness in VR is still lacking in many ways.
“You want to know if people are responding to this treatment,” Lu said. “Does it help them? It’s hard to say right now.”
About this news about neurotechnology research
Original Research: Open access.
“Graphene e-tattoos for uninterrupted ambulatory detection of electrodermal activity on the palm enabled by heterogeneous serpentine ribbons” by Hongwoo Jang et al. Nature Communications
Graphene e-tattoos for uninterrupted ambulatory detection of electrodermal activity on the palm 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 submicron thin, imperceptible graphene e-tattoos (GET) is ideal for unobstructed EDA sensing on the palm.
However, a robust electrical connection between ultrathin devices and rigid plates is a long-missing component for ambulatory use.
To minimize the well-known strain concentration at their interfaces, we propose heterogeneous serpentine ribbons (HSPR), which refer to GET serpentine partially overlapped with gold serpentine without added adhesive.
A fifty-fold stress reduction in HSPR compared to heterogeneous flat strips (HSTR) was discovered and understood. The combination of HSPR and a soft interlayer between the GET and the EDA wristband enabled ambulatory monitoring of EDA on the palm in free-living conditions.
A newly developed EDA event selection policy using unbiased phase event selection validated our GET EDA sensor against gold standards.
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