Low-Power Wearable Systems for Continuous Monitoring of Environment and Health for Chronic Respiratory Disease

Abstract

We present our efforts towards enabling a wearable sensor system that allows for the correlation of individual environmental exposures to physiologic and subsequent adverse health responses. This system will permit a better understanding of the impact of increased ozone levels and other pollutants on chronic asthma conditions. We discuss the inefficiency of existing commercial off-the-shelf components to achieve continuous monitoring and our system-level and nano-enabled efforts towards improving the wearability and power consumption. Our system consists of a wristband, a chest patch, and a handheld spirometer. We describe our preliminary efforts to achieve a sub-milliwatt system ultimately powered by the energy harvested from thermal radiation and motion of the body with the primary contributions being an ultra-low power ozone sensor, an volatile organic compounds sensor, spirometer, and the integration of these and other sensors in a multimodal sensing platform. The measured environmental parameters include ambient ozone concentration, temperature, and relative humidity. Our array of sensors also assesses heart rate via photoplethysmography and electrocardiography, respiratory rate via photoplethysmography, skin impedance, three-axis acceleration, wheezing via a microphone, and expiratory airflow. The sensors on the wristband, chest patch, and spirometer consume 0.83, 0.96, and 0.01 milliwatts respectively. The data from each sensor is continually streamed to a peripheral data aggregation device and is subsequently transferred to a dedicated server for cloud storage. Future work includes reducing the power consumption of the system-on-chip including radio to reduce the entirety of each described system in the sub-milliwatt range.

Nanomaterial‐Enabled Wearable Sensors for Healthcare

“…[4,5] In addition to the applications in wearable health monitoring, continuous tracking of daily and sports activities can offer an efficient way to assess the well-being and athletic performances. [6] In order to ensure a robust and conformal contact with the curvilinear, coarse, and dynamic surface of skin without impeding daily activities, the wearable sensor should have low modulus and high stretchability.…”

Integrated Flexible Conversion Circuit between a Flexible Photovoltaic and Supercapacitors for Powering Wearable Sensors

“…In the case of wearable sensors, energy fabrics and increasing off-grid IoT devices, there is a need for a CC capable of efficient low-wattage operation that is flexible. [31][32][33][34][35][36][37][38][39][40][41][42] In this work, we report a novel CC that is compatible with R2R manufacturing for integration with energy materials and wearable sensors. The CC incorporates a DC-DC buck-boost converter that accepts a PV input voltage range of 0.3-5.5 V and boosts to an adjustable output voltage range of 2-5.2 V across a bank of four SCs.…”

Design Considerations for Self-Powered Wearable Wireless Multimodal Vigilant Sensing Systems

“…The authors in [14] discuss the design of a system that permits a better understanding of the impact of increased ozone levels and other pollutants on chronic asthma conditions. Their system is comprised of three parts: a wristband, a chest patch, and a handheld spirometer.…”

“…For example, the authors in [12] appear to view that a system is wearable if it can be easily attached to the body and does not impede the wearer's movements, while the authors in [13] appear to view that a system is wearable if it is integrated into an article of clothing regardless of whether or not the intended measurements can be easily obtained. The authors in [14], however, appear to have a much more strict definition of wearable and view that a system is wearable if it does not burden the user in any capacity -both in wearing the system and extracting data from it. A more in-depth discussion on system wearability and how the SAP testbed is designed to be wearable is provided in section VII.…”

“…However, this is easier to do with some sensors than it is with others. Ozone sensors, for example, have a small form factor and do not require a specific location on the body, so they can easily be placed close to the energy harvester [14]. Motion sensors like accelerometers also have a small form factor, but they sometimes require placement in specific locations on the body depending on the application of the BSN.…”