Rapidly Photo-cured Resins for Customizable Earphones
Current customizable earphones that require full scanning are typically quite expensive (~ $1000) with relatively long wait times to get to the consumer (about 1 month typically). This project intends to offer customizable earphones (targeted to fit the 95% percentile of the population) at a fraction of the cost (~ $150) and can be done within a few minutes. The basis is to enclose a photocurable resin in a thermoplastic polyurethane (TPU) sleeve on which an array of blue LEDs is arranged. The TPU must be modelled appropriately to fit the ear before it is filled with the monomers for the curing resin, after which the final optimized fit is obtained. Once fit into the ear, the LEDs are turned on, curing the resin in < 30 sec. We have developed a curable monomer/initiator system with an acceptable exotherm (~10 oC) but mechanical properties needs to be tailored for optimal comfort. Further, the interface between the TPU and cured resin must be sufficiently strong to avoid delamination and tearing. Finally, shrinkage of the cured resin must be avoided. We will use experimental design to manipulate the monomer mixture to attain the appropriate mechanical properties (tensile) and to use attenuated FT-IR to measure degree of cure (a critical parameter for mechanical properties, shrinkage and health concerns). The intern will develop a system with desirable mechanical properties (modulus, elongation at break) as well as minimal shrinkage (hopefully < 2-3%) and sufficient interfacial strength (estimated from peel/adhesion tests).