mechanical testing of on body delivery systems 


Testing Wearable Devices Used in the Treatment of Diabetes and Other Chronic Illnesses

Trends in wearable technology follow those of the broader biomedical and electronics industries — devices are getting smaller, smarter, and easier to use. These wearable devices range from on-body drug delivery systems for diabetes and cancer treatment to electrical nerve stimulation patches or sensors t monitor vitals. All treatments increase patient autonomy and are rapidly increasing in popularity in light of higher incidence rates of chronic disease and an aging population. As this trend continues, manufacturers are working to develop robust testing methods to mechanically evaluate all aspects of these devices and ensure that they are performing as expected. For more information on other biomedical applications, visit our Biomedical Industry page.


On Body Delivery Systems (OBDS) represent a quickly growing segment of the injectable drug delivery device market. These devices offer unique advantages over more traditional delivery methods. One of their most differentiating features is their ability to support significantly larger volumes of medication than devices like prefilled syringes and autoinjectors, with some OBDS reaching as much as 10 mL of deliverable volume. This is a direct result of the explosion of large molecule biologics, whose efficacy requires higher concentrations and subsequently higher volume in solution. OBDS also simplify patient adherence, as the entire delivery process occurs automatically once the device is placed and activated. In addition, their form factor allows for easier integration of IOT functionality, helping create companion applications to track and monitor patient progress.

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Though these devices are just recently starting to be commercialized on drug platforms, the testing requirements are becoming more standardized. ISO 11608-6 was released in 2022, which is the first official standard that provides guidance around evaluating the functionality of OBDS. At this point, the testing specifications are still purposefully broad to apply to a range of devices with different form factors. The dose accuracy, injection time, delivery profile, and needle extension are relatively agnostic of the device, requiring additional testing system capabilities such as an integrated scale and camera. Testing around the properties of the medical grade adhesives is subject to the most uncertainty, with references to a wide range of existing adhesive test standards.

Challenge #1 - Flexibility Around Device Form Factors

The overall size and functionality of OBDS can vary greatly between manufacturers, and mechanical testing systems are not inherently designed for evaluating such a varied set of products. The dimensions of OBDS necessitate testing systems with a large fixturing surface that has sufficient anchoring points to accommodate all profiles. The use of a component test plate - a tapped platform with regularly spaces threaded connections - provides the most flexibility for customers to create their own fixturing for their devices. A unique challenge to OBDS is the potential for activation mechanisms and needles which are not collinear. An adjustable load cell mount makes it possible to maintain the needle centered on the injection point while ensuring the load cell is aligned with the activation button.

Challenge #2 - Capturing Extended Dose Profiles

wearable autoinjector being tested

Autoinjectors typically dispense their entire volume of fluid at a consistent rate in the range of 1 to 10 seconds. OBDS will work on a longer time scale to address patient comfort associated with large volume injections. In some cases, the delivery profile will vary throughout the duration of the injection to optimize drug absorption. The use of an integrated scale measurement in Bluehill Universal allows for proper visualization representation of the dose profile , aligning with the guidance of the ISO 11608-6 standard [Annex B].

Challenge #3 - Adhesive Evaluations

ISO 11608-6 points toward established standards like ASTM D3330 for characterizing the fundamental adhesive properties of the adhesive materials used to affix devices to patients' skin. This standard provides an ideal baseline for comparative testing of different adhesives, but does not accurately represent the real-world adhesive properties. To do this, the testing system must also be able to support more realistic substrates and preconditioning parameters such as temperature and moisture. A system with cyclic loading capabilities may provide additional insights in evaluating the degradation of adhesive properties after hours of simulated use.