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IBOA-free light-curing adhesive solves skin compatibility problems with CGM sensors and other wearables
DELO has achieved a major success in medical technology with DELO PHOTOBOND MG4047. With this product, the company is launching an IBOA-free light-curing adhesive specifically for CGM systems and other medical wearables. This innovation could significantly improve the lives of millions of diabetes patients and other users of medical wearables.
IBOA-free adhesive
Continuous glucose monitoring (CGM) has revolutionized the lives of diabetes patients. CGM systems continuously measure blood sugar levels via a sensor placed under the skin and send the data to a smartphone or separate receiver. Unlike conventional blood sugar measurements involving finger pricks, CGM users receive current values every one to five minutes and are warned of dangerous blood sugar fluctuations.
However, CGM technology comes with a significant problem. Skin reactions at the attachment site. Many patients develop skin irritation, redness, or even allergic reactions from their medical wearables. Studies show that over 40% of users are affected.
The most common cause is the adhesive itself, which irritates the skin, especially when changing the sensor. In most cases, this is irritant contact dermatitis—a mechanical or chemical skin irritation, not a true allergy. The skin reacts to the adhesive, to sweat that collects under the patch, or to the sensor coming off, similar to a patch that is too tight.
Less common, but still possible, are genuine allergic reactions to ingredients in the patch. One example is IBOA (isobornyl acrylate), a chemical compound that makes adhesives flexible and durable. This substance can be released from the material when it comes into contact with sweat or moisture and cause skin reactions. Such an allergy manifests itself in severe itching, blistering, and pronounced rashes, which often only appear months after the first application.
DELO PHOTOBOND MG4047 completely dispenses with IBOA and other problematic substances. Instead, the biocompatible adhesive relies on a new polymer formulation that is both skin-friendly and technically efficient.
The absence of IBOA significantly reduces the risk of contact sensitization in medical wearables. With repeated skin contact, even small amounts of substances containing IBOA can lead to sensitization, causing the immune system to overreact. Once sensitized, CGM users react to even the slightest traces of IBOA with skin eczema or other allergic reactions.
Sensor drift refers to the gradual deterioration of a sensor's measurement accuracy over time—the values "drift" away from the actual values without any change in the measurement conditions. This problem can be dangerous in CGM systems and, in the worst case, lead to life-threatening situations. For example, the sensor may display 120 mg/dL, while the actual blood glucose level is 80 mg/dL – a critical hypoglycemia would be overlooked.
Inaccurate trend displays are particularly problematic, as they mean that patients are not warned in time about critical blood sugar fluctuations. In dangerous situations, hypoglycemia can go unnoticed, which could lead to loss of consciousness or diabetic coma. At the same time, the resulting need for more frequent calibration via finger prick measurements negates the convenience advantage of CGM technology.
An exploded view of a glucose monitoring sensor, including the adhesive bondlines for its assembly (shown in magenta)
DELO PHOTOBOND MG4047
DELO's biocompatible and IBOA-free solution PHOTOBOND MG4047 specifically addresses these problems. With low water absorption of only 0.15 percent by weight and low water permeation of 13 (g·mm)/(m²·24h), the adhesive creates an effective water vapor barrier and prevents moisture from penetrating the CGM electronics.
The flexible material properties, with an elasticity modulus of 230 MPa and 200 percent elongation at break, reduce mechanical stresses caused by body movements, thereby minimizing mechanically induced sensor drift. At the same time, the stable encapsulation of the CGM electronics by the light-curing adhesive provides long-lasting protection against chemical reactions and protein deposits, maintaining measurement accuracy throughout the entire wearing period of 7 to 14 days.
The efficiency of the curing process is crucial for the mass production of CGM systems and other medical wearables. The biocompatible PHOTOBOND MG4047 cures completely after just two seconds of LED light at an intensity of 1000 mW/cm². The wavelengths used, 365 and 400 nanometers, correspond to standard LED systems, which facilitates integration into existing production lines for medical wearables.
This speed is a huge advantage for manufacturers of CGM systems and means significantly higher production throughputs at lower manufacturing costs.
DELO PHOTOBOND MG4047 proves its biocompatibility by meeting the requirements of the cytotoxicity test according to DIN EN ISO 10993-5. This test examines whether materials have harmful effects on living cells by exposing cell cultures to direct contact with the test material or its extracts. The test measures whether and to what extent cells die or their morphology (shape/growth) is disturbed.
In addition, the adhesive complies with EU RoHS Directive 2015/863, which serves to ensure the non-toxicity of substances in electronic devices. This directive prohibits or restricts substances such as lead, mercury, cadmium, or certain flame retardants that are problematic for both human health and the environment.
The market for medical wearables and CGM technology is growing rapidly. The CGM market alone is expected to reach a volume of over $28-30 billion by 2030. This growth is driven by the increasing number of diabetes patients worldwide and the trend toward preventive health monitoring through medical wearables.
Exploded view of biosensor electrode with adhesive application regions highlighted in magenta
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With this comprehensive biocompatibility testing, the IBOA-free DELO PHOTOBOND MG4047 paves the way for more comfortable and safer medical wearables.
If you would like more information about DELO PHOTBOND and our other solutions, please contact us. Our experts are here to help you plan your projects efficiently and implement them successfully.
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DELO is a leading provider of high-tech adhesives and has been offering solutions for the semiconductor, automotive, and electronics industries for over 25 years. Our innovative technologies set industry standards. Companies such as Bosch, Huawei, and Siemens trust DELO when it comes to superior adhesive technologies.
