Design, fabrication and investigation of temperature-sensitive polymer microdroplets produced by the flow-focusing microchannel under the heat produced by the flexible microheater

This study aimed to produce drops that can be used in wound dressings with controlled drug release for the treatment of skin disorders and chronic wounds. The lack of precise control of drug delivery to the wound area in common approaches has prompted us to design a controllable wound dressing. The dressing was designed with three main components: the drug delivery, stimulation, and control systems. A flexible microheater was fabricated by sputtering gold and gold/titanium onto a polymer substrate, aiming to stimulate microcarriers. The electrical resistance of gold and gold/titanium microheaters was measured at about 220 and 150 ohms respectively. By using the photolithography method, a microchannel focused on the flow was designed, and subsequently, NIPAM droplets were produced as a potential drug delivery system The microchannel performance assessment demonstrated consistent droplet production, allowing for the extraction of droplets measuring 360 to 515 micrometers in diameter at the outlet by modifying the flow rate ratio within the microchannel. The temperature sensitivity of the microparticles was evaluated, and a 40% decrease in droplet diameter was observed when going from 18°C ​​to 32°C. The studied drug carriers showed positive and acceptable results for use in a smart dressing, which enables stable control over the drug release rate by the heat generated in the flexible microheater