Stress in daily life has become a significant issue due to health risks. Because many sources of stress are unavoidable, management of stress is critical. Recent wearable devices, detecting physiological signals such as electrodermal activity, have been developed for quantitative and practical stress management assessment. However, they rely on a rigid and bulky system that is uncomfortable to wear during daily activities and has significant motion artifact issues. Here, we introduce a wireless skin-conformal bioelectronic system that evaluates daily stress management. Ultrathin, stretchable circuit system incorporated with a silicone elastomer enables a soft lamination on the skin, providing portable, continuous monitoring of stress. Printed, biocompatible nanomembrane electrodes on a breathable silicone tape provide long-term wearability and skin compatibility, enabling seamless monitoring of galvanic skin response at home with daily activities. Demonstration of stress management practice with human subjects shows the effectiveness of stress alleviation with a promising, non-invasive, and portable wearable system.
A leading cause of death in the US is cardiovascular disease, of which approximately 44% are attributable to coronary artery disease. A minimally invasive procedure with stent placement has drastically improved the outcomes. However, there are still relatively high percentages of a life-threatening complication called "restenosis" (i.e., re-narrowing of a coronary artery). Here, we introduce an imperceptible nanostructured electronic stent that incorporates an ultrathin stretchable wireless sensor with a stent for continuous surveillance of restenosis along with neointimal proliferation and plaque deposition. The low-profile, nanomembrane capacitive strain sensor is constructed by the printing of conductive nanoparticles and polymers on a soft elastomeric membrane. This sensor is capable of detecting strains as low as 0.15% with a sensitivity of 3% per linear strain. The sensor performance is suitable to detect small alterations produced in the coronary artery with the progression of restenosis under typical pulsatile flow. In addition, an in vitro testing platform has been developed to accurately evaluate the sensor's performance. Both numerical analysis and computational fluid dynamics (CFD) were used to design the artery model with various levels of restenosis. The strain plots of artery models from both numerical and computational analyses have successfully shown the relationship between the strain and restenosis levels, varied pressures, artery lumens, and artery thicknesses. Our recent outcomes will provide better solutions for both diagnostic heart disease and many other vascular diseases that require stents.
Heart disease is the most common cause of death, so there is a great need for non-invasive continuous monitoring of heart activities in daily life for early diagnosis and treatment. However, existing devices are not suitable for long-term use since they are uncomfortable to wear and heavy due to rigid plastics and thick metals. Here, we introduce a low-profile, comfortable, skin-wearable multifunctional biopatch, capable of wireless monitoring of heart and motion activities. The combination of a thin, tacky elastomeric membrane, skin-like stretchable electrodes, and a small form factor flexible circuit ensures the intimate integration of the device on the skin in adhesive and gel electrolyte-free environment. The results are not only enhanced user comfort and minimized motion artifacts during normal activities but also accurate classifications for various arrhythmias based on R-R interval and ST-segment analysis. In addition, the integrated motion sensor is available to track human activities and alert an emergency when a fall event occurs. This multifunctional soft wearable system would serve as a new wearable tool to advance human healthcare.
Recent advances in materials engineering, chip miniaturization, wireless communication, power management, and manufacturing technologies have shaped our perspectives on wearable electronics in ways that wearing a Fitbit is as casual as driving to work. However, establishing a robust sensor-to-skin interface remains as a significant challenge due to the drastic contrast in soft, dynamic human skin and rigid electronics, limiting the adoption of technology to leisurebased applications. Here, we present an engineering solution by combining the respective merits of thin-film nanostructures, soft materials, and miniature electronic components and developing a soft, hybrid, wireless, wearable platform. We exploit conventional CMOS processes to fabricate metal/polymer nanostructures, implemented as dry contact electrodes (thickness ~3 μm) as well as a flexible interconnection system (thickness ~10 μm). The electrodes are further optimized by incorporating an open-mesh network geometric features allowing for prolonged, intimate contact throughout repeated and dynamic deformation of human skin. The skin-electrode impedance and the signal-to-noise ratio are ~18 kΩ and 29.52 dB, respectively, from electromyogram (EMG) recordings, matching the qualities of Ag/AgCl hydrogel electrodes. The stretchable circuit layer contains pad metal structures compatible for integration of surface mount chip components using a conventional reflow soldering process, allowing for easy integration of commercially available integrated circuit solutions. Silicone-based elastomer is used as both the carrier substrate for the thin-film structures and the backing layer providing the necessary adhesiveness to the skin. We verify that the completed system can be stretched up to 10% based on computational and experimental analysis. Finally, we demonstrate the robustness of the system functionality by showcasing human-machine interfaces (HMI) based on a single-channel forearm EMG with a real-time classification distinguishing four different hand gestures (accuracy: 95.9%) as well as the control of a robotic hand using three devices simultaneously.
Skin-mounted epidermal electronics, a strategy for bio-integrated electronics, provide an avenue to non-invasive monitoring of clinically relevant physiological signals for healthcare applications. Current conventional systems consist of single-point sensors fastened to the skin with adhesives, and sometimes with conducting gels, which limits their use outside of clinical settings due to loss of adhesion and irritation to the user. In order to facilitate extended use of skin-mounted healthcare sensors without disrupting everyday life, we envision electronic monitoring systems that integrate seamlessly with the skin below the notice of the user. This manuscript reviews recent significant results towards our goal of wearable electronic sensor systems for long-term monitoring of physiological signals. Ultra-thin epidermal electronic systems (EES) are demonstrated for extended use on the skin, in a conformal manner, including during everyday bathing and sleeping activities. We describe the assessment of clinically relevant physiological parameters, such as electrocardiograms (ECG), electromyograms (EMG), electroencephalograms (EEG), temperature, mechanical strain and thermal conductivity, using examples of multifunctional EES devices. Additionally, we demonstrate capability for real life application of EES by monitoring the system functionality, which has no discernible change, during cyclic fatigue testing.
Nucleic acids circulating in body fluids are drawing great attention due to their potential use for disease diagnostics and
prognostics. Current detection methods have yet to demonstrate the capability to selectively detect the low abundance
nucleic acids. The challenge lies in the separation of circulating DNA from the genomic DNA in normal cells.
Here we present an approach employing a nano-structured tip, which directly concentrates nucleic acids to the tip from a
sample solution. The high aspect ratio tip is able to collect nucleic acid molecules out of a buffer solution by using
dielectrophoretic (DEP) and surface tension force. The DEP force attracts DNA and other biomolecules in the vicinity of
a nanotip from the sample solution. Among the attracted molecules, circulating nucleic acids whose dimensions are
much smaller than the nanotip diameter are selectively captured to the tip while other bioparticles comparable to or
larger than the tip diameter remain in the solution due to surface tension induced force. The concentrated DNA molecules are characterized by SEM, X-ray, and fluorescent microscopy, which demonstrate DNA capturing out of a sample solution having a 1pg/mL DNA concentration. The nanotip-based capturing method will facilitate rapid, but highly sensitive detection of circulating DNA directly from minimally treated- or raw samples.