SBIR Fast-Track: Strain Sensing Smart Skin (S4) for Structural Testing and Health Monitoring

The broader/commercial impact of this Small Business Innovation Research (SBIR) Fast-Track project is developing a novel technology for industrial strain measurements. Strain, the deformation of an object when exposed to large forces, is routinely measured by many heavy industries when testing structures to ensure their safety. Despite the widespread need for strain measurements, all currently available methods have some drawbacks. By gaining a deeper understanding of carbon nanotubes, an advanced material, this project will use nanotube physical properties in a new kind of strain sensor that is monitored using light. The technology fills performance gaps left by other methods and will offer economic value to industrial adopters while improving safety testing of critical infrastructure. Commercialization will benefit from a durable competitive advantage based on intellectual property and technical expertise. Customers may purchase strain measurement services, or alternatively buy the unique equipment, materials, and training needed to perform measurements themselves. Commercial success of the company depends entirely on the value of the new technology. The initial customers will be aerospace manufacturing firms, because they maintain high standards for product safety and need extensive strain measurements when certifying airframes. This Small Business Innovation Research (SBIR) Fast-Track project will use the unique spectroscopic properties of single-wall carbon nanotubes to commercialize a new technology for industrial strain measurement. Among the few existing strain measurement methods, only digital image correlation can provide two-dimensional strain maps, and it performs poorly in the few-millistrain regime, near holes and discontinuities, and for strains accumulated when the specimen is not constantly observed. The new technology overcomes these drawbacks. In it, specimens are coated with a polymer film containing dilute carbon nanotubes that serve as microscopic strain gauges. The specimen strain at any position is found by exciting the surface with visible laser light and measuring small shifts in the resulting near-infrared nanotube emission spectrum to deduce local strain. A custom apparatus captures hyperspectral fluorescence images used to find peak shifts. This project will address technical goals that must be met for the commercial product. Goals include improving sensor linearity at higher strain levels, adapting the coating application for rough or scattering surfaces, increasing measurement speed, developing water-based and durable sensing films, and improving software usability. The project results will enable the introduction of a novel, commercially viable product for industrial strain mapping. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.