Patients with type II diabetes experience chronic wounds, a condition where wounds fail to self-heal after 3 months. Physiological processes leading to wound healing such as vascularization are disrupted and biofilms form on the wound bed that are resistant to topical antibiotics treatment. Dr. Ali Tamayol and his team from the University of Nebraska-Lincoln published a study in the journal of Advanced Functional Materials about a wearable and programmable bandage that can deliver vital drugs into the deeper layers of the wound bed, past the biofilm. They achieve this with miniaturized needle arrays (MNAs) that induce minimal pain and inflammation compared to other invasive methods. The programmable portion allows a physician to remotely administer therapeutics as needed.
To fabricate the MNAs, the team used a multimaterial 3D printer that created hollow MNAs out of a biocompatible resin. Needle spacings, needle lengths, base sizes and opening diameters could be customized for various wound types. To investigate the mechanical properties of the printed needles (more specifically its breakage force), compression force testing with the CellScale UniVert was done at 200N. This same instrument was also employed to investigate penetration and retraction force of the MNAs on pig skin (see image below), as well as the bonding strength of the MNA island to a PDMS substrate holding microchannels for drug delivery.