IBOA-free medical adhesive for glucose monitoring sensors and other wearables

DELO has released a new light-curing medical-grade adhesive engineered with nontoxicity in mind. DELO PHOTOBOND MG4047 has been created for wearable medical applications such as glucose monitoring sensors (CGM). Its chemical properties and impermeable characteristics prevent skin irritation in cases of media influence, such as rain or sweat.

With a 230-MPa Young’s modulus and a 200% elongation at tear, while maintaining a 9-MPa compression shear strength, the adhesive manages to be highly flexible and decidedly strong. These physical properties prevent common problems associated with wearable sensors, such as sensor drift, which can occur following potting.

Chief among its advantages is that it is IBOA-free. IBOA, or isobornyl acrylate, is a chemical compound found in many polymer materials and is considered an extractable material. If medical wearables worn by patients are exposed to external media such as rain or sweat, tiny particles may leak out and contact the skin, causing adverse reactions such as irritation or allergies. Being free from IBOA reduces the risk of such reactions.

The adhesive demonstrates its nontoxicity through its biocompatibility, meeting the requirements outlined in the DIN EN ISO 10993-5 cytotoxicity test. It also complies with EU RoHS Directive 2015/863, which is used to ensure nontoxicity in substances used in electronic equipment.

As well as biocompatibility, DELO PHOTOBOND MG4047 attains low water absorption at 0.15wt%, resulting in low water permeation at 13 (g·mm)/(m²·24h). This creates a high water vapour barrier and prevents potential contact with other leachable substances.

The curing properties of this light-curing adhesive are optimised for mass medical wearable production with a required irradiation time of as little as two seconds under a 365–400-nm LED light with an intensity of 1000mW/cm².