Description
Non-destructive testing using multiple wavelengths is essential because the items inspected for foreign matter in daily-use goods and industrial products on factory production lines are composed of multiple materials. Carbon nanotubes (CNTs) can be dissolved in a solvent and printed on substrates. Printed CNT thin films can be applied as multi-wavelength sensors for non-destructive testing, since they have an inherent ultrabroadband (Terahertz, Infrared (near-infrared, mid-infrared, and far-infrared), Visible light, and Ultraviolet) and highly efficient photo-absorption. The operating mechanism of the CNT film sensor is the photo-thermoelectric (PTE) effect. This mechanism, photo-absorption triggered by external photo-irradiation, locally induces a temperature enhancement at the interface between dissimilar materials, and thermoelectric conversion of the temperature gradient across the PTE sensor provides direct-current voltage (DCV) signals. Multi-wavelength Computed Tomography (CT) inspection using CNT sensors enables the reconstruction of the internal structure and material identification of objects composed of multiple materials. Non-destructive testing using CNT sensors is highly safe, non-contact, and non-invasive, employing photo-irradiation with lower energy than the X-rays typically used. This work aims to improve the spatial resolution of CT inspections by using electrohydrodynamic (EHD) inkjet printing to perform micro-printing of CNT sensor array devices. In non-destructive testing, the sensor element density is critical for obtaining high-resolution images. Conventional dispenser printing had a limit of 500 μm pitch, which restricted spatial resolution. Furthermore, because CNTs are highly agglomerative, nozzle clogging is a major challenge. The EHD inkjet can eject droplets smaller than the nozzle diameter, enabling printing with line widths of 100 μm or less. In this study, we achieved CNT printing at a pitch of 50 μm, which is one-tenth that of dispenser printing.
| I am the presenting author | Yes |
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