Briana Morey

A stretchable and flexible system for skin-mounted measurement of motion tracking and physiological signals

In this paper, we present a stretchable wearable system capable of i) measuring multiple physiological parameters and ii) transmitting data via radio frequency to a smart phone. The electrical architecture consists of ultra thin sensors (<; 20 μm thick) and a conformal network of associated active and passive electronics in a mesh-like geometry that can mechanically couple with the curvilinear surfaces of the human body. Spring-like metal interconnects between individual chips on board the device allow the system to accommodate strains approaching ~30% A representative example of a smart patch that measures movement and electromyography (EMG) signals highlights the utility of this new class of medical skin-mounted system in monitoring a broad range of neuromuscular and cardiovascular diseases.

Epidermal electronics: Skin sweat patch

An ultrathin, stretchable, and conformal sensor system for skin-mounted sweat measurement is characterized and demonstrated in this paper. As an epidermal device, the sweat sensor is mechanically designed for comfortable wear on the skin by employing interdigitated electrodes connected via stretchable serpentine-shaped conductors. Experimental results show that the sensor is sensitive to measuring frequency, sweat level and stretching deformation. It was found that 20kHz signals provide the most sensitive performance: electrical impedance changes 50% while sweat level increases from 20 to 80. In addition, sensor elongation from 15 up to 50% affected the measurement sensitivity of both electrical impedance and capacitance.

A conformal sensor for wireless sweat level monitoring

A conformal, wearable and wireless system for continuously monitoring the local body sweat loss during exercise is demonstrated in this work. The sensor system includes a sweat absorber, an inter-digitated capacitance sensor, and a communication hub for data processing and transmission. Experimental results show that the sensor has excellent sensitivity and consistent response to sweat rate and level. A 150% variation in the sensor capacitance is observed with 50μL/cm2 of sweat collected in the absorber. During wear tests, the sensor system is placed on the subjects right anterior thigh for measuring the local sweat response during exercise (eg. running), and the measured sweat loss (147μL) was verified by the weight change within the absorbent material (144mg). With a conformal and wireless design, this system is ideal for applications in sport performance, dehydration monitoring, and health assessment.

Epidermal electronics for seamless monitoring of biopotential signals

Medical deployment of electronics is often hampered by boxy and rigid packaging. Biological tissues are soft and curved, while electronic components are hard and angular. The mechanical mismatch can be improved by re-packaging electronics in radical new form factors. We present a technology platform using ultra-thin components linked with conformal interconnects and embedded in low modulus polymers to provide an excellent match to biological tissues. This technology platform builds on the pioneering work by Prof. John Rogers @ UIUC. [1, 2] Rather than developing novel semiconducting, conducting and insulating materials, the platform exploits the concept that only the top 5-15 μm of a silicon IC contributes to functional behavior. Similar considerations apply to other high performance components such as LEDs and photodiodes. The thin active layer can be removed and transferred to polymer by various processes, which we discuss below. The resulting thin and flexible silicon islands can be interconnected using metallization patterned to permit substantial macro-scale deformation while experiencing minimal micro-scale deformation, just as a coiled spring can stretch several times its own length while keeping the local metal strain within the elastic limit. On-body and in-body applications are both well suited to the technology platform. Epidermal electronics are skin-mounted systems that resemble electronic tattoos, and can be worn for extended periods without discomfort while providing continuous monitoring. In this paper, we discuss in detail, the following technologies and concepts that enable epidermal electronics: (1) Advanced die preparation methodologies that allow for thinning, placement, and attachment of sub-50μm commercial IC devices (COTS); (2) die embedding methods in flexible polymer substrates; (3) use of conformal metal interconnects to connect components; and (4) elastomer stacking optimized for application strain and compatibility with biological tissue. We present data of thinned COTS ICs embedded in flex test circuits to demonstrate the technology.

Archipelago platform for skin-mounted wearable and stretchable electronics

In this investigation, the “archipelago” design is presented as a platform for skin-mounted wearable and stretchable electronics. The electronic components of the design were distributed between islands connected by stretchable serpentine structures. The analytical results show that at 20% overall elongation, the serpentines stretch 60% due to the rigidity of the islands. This 20% elongation is defined as the system stretchability. The 60% elongation on the serpentines is defined as the effective stretchability. At 60% effective stretch, the calculated equivalent plastic strain in a serpentine interconnect is 0.67%, which is well below the fracture limit of copper. Elongation experiments show that the archipelago structure has the system stretchability up to 76% for one-time-stretching, translating to 228% of the effective stretchability on the serpentines. Fatigue-tension experiments show that at 20% system stretch, the archipelago structure can withstand on average 71,950 cycles without electrical or mechanical degradation.

Multifunctional Epidermal Sensor Systems with Ultrathin Encapsulation Packaging for Health Monitoring

Wearable sensors have the potential to enable longitudinal, objective health monitoring in patients with chronic diseases, including cardiac rhythm disorders, neurological and movement disorders, diabetes, and pain. However, conventional wearable devices are typically comprised of rigid, packaged electronics, which may compromise overall signal fidelity and wearer comfort during activities of daily living and sleep. In this chapter, we present recent advances in the development of thin and stretchable epidermal systems for biometric data measurements. These non-invasive epidermal systems are fully integrated with multiple sensors, an analog front end module, a radio for wireless communication , onboard flash memory, a rechargeable battery all encapsulated in a soft, stretchable and water-resistant silicone, and with an air permeable adhesive layer that interfaces with the human skin. The encapsulated system intimately couples with the skin at multiple locations on the body. We present results showing the potential of this technology to quantitatively assess bio-kinematics and electrophysiological signals. Finally, we provide perspectives on remaining challenges and opportunities to achieve clinical validation and commercial adoption of these technologies.

Multifunctional Epidermal Sensor Systemswith Ultrathin Encapsulation Packagingfor Health Monitoring

Wearable sensors have the potential to enable longitudinal, objective health monitoring in patients with chronic diseases, including cardiac rhythm disorders, neurological and movement disorders, diabetes, and pain. However, conventional wearable devices are typically comprised of rigid, packaged electronics, which may compromise overall signal fidelity and wearer comfort during activities of daily living and sleep. In this chapter, we present recent advances in the development of thin and stretchable epidermal systems for biometric data measurements. These non-invasive epidermal systems are fully integrated with multiple sensors, an analog front end module, a radio for wireless communication , onboard flash memory, a rechargeable battery all encapsulated in a soft, stretchable and water-resistant silicone, and with an air permeable adhesive layer that interfaces with the human skin. The encapsulated system intimately couples with the skin at multiple locations on the body. We present results showing the potential of this technology to quantitatively assess bio-kinematics and electrophysiological signals. Finally, we provide perspectives on remaining challenges and opportunities to achieve clinical validation and commercial adoption of these technologies.

Multifunctional Epidermal Sensor SystemsEpidermal Electronics Multifunctional Epidermal Sensor Systems with Ultrathin Encapsulation PackagingUltraThin Encapsulation Packaging for Health MonitoringMultifunctional Epidermal Sensor Systems

Wearable sensors have the potential to enable longitudinal, objective health monitoring in patients with chronic diseases, including cardiac rhythm disorders, neurological and movement disorders, diabetes, and pain. However, conventional wearable devices are typically comprised of rigid, packaged electronics, which may compromise overall signal fidelity and wearer comfort during activities of daily living and sleep. In this chapter, we present recent advances in the development of thin and stretchable epidermal systems for biometric data measurements. These non-invasive epidermal systems are fully integrated with multiple sensors, an analog front end module, a radio for wireless communication , onboard flash memory, a rechargeable battery all encapsulated in a soft, stretchable and water-resistant silicone, and with an air permeable adhesive layer that interfaces with the human skin. The encapsulated system intimately couples with the skin at multiple locations on the body. We present results showing the potential of this technology to quantitatively assess bio-kinematics and electrophysiological signals. Finally, we provide perspectives on remaining challenges and opportunities to achieve clinical validation and commercial adoption of these technologies.

Multifunctional Epidermal Sensor Systems Multifunctional Epidermal Sensor Systems with Ultrathin Encapsulation Packaging for Health Monitoring

Wearable sensors have the potential to enable longitudinal, objective health monitoring in patients with chronic diseases, including cardiac rhythm disorders, neurological and movement disorders, diabetes, and pain. However, conventional wearable devices are typically comprised of rigid, packaged electronics, which may compromise overall signal fidelity and wearer comfort during activities of daily living and sleep. In this chapter, we present recent advances in the development of thin and stretchable epidermal systems for biometric data measurements. These non-invasive epidermal systems are fully integrated with multiple sensors, an analog front end module, a radio for wireless communication , onboard flash memory, a rechargeable battery all encapsulated in a soft, stretchable and water-resistant silicone, and with an air permeable adhesive layer that interfaces with the human skin. The encapsulated system intimately couples with the skin at multiple locations on the body. We present results showing the potential of this technology to quantitatively assess bio-kinematics and electrophysiological signals. Finally, we provide perspectives on remaining challenges and opportunities to achieve clinical validation and commercial adoption of these technologies.

Multifunctional Epidermal Sensor SystemsEpidermal ElectronicsMultifunctional Epidermal Sensor Systemswith Ultrathin Encapsulation PackagingUltraThin Encapsulation Packagingfor Health MonitoringMultifunctional Epidermal Sensor Systems

Wearable sensors have the potential to enable longitudinal, objective health monitoring in patients with chronic diseases, including cardiac rhythm disorders, neurological and movement disorders, diabetes, and pain. However, conventional wearable devices are typically comprised of rigid, packaged electronics, which may compromise overall signal fidelity and wearer comfort during activities of daily living and sleep. In this chapter, we present recent advances in the development of thin and stretchable epidermal systems for biometric data measurements. These non-invasive epidermal systems are fully integrated with multiple sensors, an analog front end module, a radio for wireless communication , onboard flash memory, a rechargeable battery all encapsulated in a soft, stretchable and water-resistant silicone, and with an air permeable adhesive layer that interfaces with the human skin. The encapsulated system intimately couples with the skin at multiple locations on the body. We present results showing the potential of this technology to quantitatively assess bio-kinematics and electrophysiological signals. Finally, we provide perspectives on remaining challenges and opportunities to achieve clinical validation and commercial adoption of these technologies.