Project title: Densely Distributed Sensing using Nanocomposite Fabric Sensors
Source of support: University of California, San Diego

Human performance sensing, whether it's for monitoring the well-being of hospital 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 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). 

Fig. 1. A nanocomposite fabric sensor is subjected to distributed pressure sensing tests in the laboratory.

Fig. 3. Nanocomposite fabric sensors are highly flexible and can sustain large deformations and even hand-washing. 

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.