A UC San Diego Center for Healthy Aging and Office of Naval Research funded project.
Project title: Densely Distributed Sensing using Nanocomposite Fabric Sensors
Source of support: Office of Naval Research, Sony, and the University of California San Diego
Human performance sensing, whether it's for monitoring the well-being of patients, military personnel in the field, or first responders at a disaster site, is important for safeguarding the human subject. Advancements in wearable technology and sensors have brought forth new devices and systems that have facilitated human performance sensing at significantly lower costs than before. Unfortunately, most of these wearable sensors utilize discrete electronic transducers that are tethered, bulky, rigid, and uncomfortable for the end-user. This research seeks to address the aforementioned limitations by developing carbon nanotube (CNT)-based and graphene nanosheet (GNS)-based fabric sensors that are capable of accurately measuring various stimuli over the entire fabric surface. Here, piezoresistive CNT-polymer thin films have been fabricated and integrated with flexible fabric (Fig. 1). Instead of measuring the fabric's change in electrical properties at every location, an electrical impedance tomography algorithm uses boundary excitations and voltage measurements to estimate the electrical properties of the entire fabric (Fig. 2). These nanocomposite fabric sensors have been validated for distributed pressure sensing (Fig. 2), spatial strain/deformation monitoring, human respiration rate monitoring, and body temperature monitoring. Overall, the fabric sensors offer advantages such as being flexible, low-cost, simple to fabricate, non-intrusive, washable, and is comfortable to wear (Fig. 3).
Prof. Wei-Hung Chiang, National Taiwan University of Science and Technology
Prof. Eric Hekler, UC San Diego School of Public Health
Prof./Dr. Alison Moore, UC San Diego School of Medicine
Prof. m.c. schraefel, University of Southampton (UK)
Prof. Sheng Xu, UC San Diego, Jacobs School of Engineering
Naval Health Research Center
Naval Medical Center San Diego
Y-A. Lin, m.c. schraefl, W-H. Chiang, and K. J. Loh, 2021, “Wearable Nanocomposite Kinesiology Tape for Monitoring Muscle Engagement,” MRS Advances (2059-8521), Springer. DOI: 10.1557/s43580-021-00005-4
Y-A. Lin, Y. Zhao, L. Wang, Y. Park, Y-J. Yeh, W-H. Chiang, and K. J. Loh, 2021, "Graphene K-Tape Meshes for Densely Distributed Human Motion Monitoring," Advanced Materials Technologies (2365-709X), Wiley, 6(1): 2000861. DOI: 10.1002/admt.2020000861
K. Manna, L. Wang, K. J. Loh, and W-H. Chiang, 2019, "Printed Strain Sensors Using Graphene Nanosheets Prepared by Water-Assisted Liquid Phase Exfoliation,” Advanced Materials Interfaces (2196-7350), Wiley, 1900034. DOI: 10.1002/admi.201900034 :: Article featured on Back Cover
L. Wang, K. J. Loh, W-H. Chiang, and K. Manna, 2018, "Micro-Patterned Graphene Sensing Skins for Human Physiological Monitoring" Nanotechnology (0957-4484), IOP, 29(10): 055018/1-11. DOI: 10.1088/1361-665X/aa6849 :: This work is featured by Nanotechweb.org: Nano-ink-based sensors detect an eye blink
L. Wang and K. J. Loh, 2017, "Wearable Carbon Nanotube-based Fabric Sensors for Monitoring Human Physiological Performance," Smart Materials and Structures (0964-1726), IOP, 26: 055018/1-11. DOI: 10.1088/1361-665X/aa6849
L. Wang, S. Gupta, K. J. Loh, and H. S. Koo, 2016, "Distributed Pressure Sensing using Carbon Nanotube Fabrics," IEEE Sensors (1530-437X), IEEE, 16(12): 4663-4664. DOI: 10.1109/JSEN.2016.2553045
Fig. 1. A nanocomposite fabric sensor is subjected to distributed pressure sensing tests in the laboratory.
Fig. 2. The electrical impedance tomography algorithm outputs the spatial conductivity maps of the fabric sensor, and localized changes in electrical properties correspond to the severity and location of applied pressure.
Fig. 3. Nanocomposite fabric sensors are highly flexible and can sustain large deformations and even hand-washing.