Medical devices need to function correctly throughout their lifespan, including being able to withstand the demands of daily use. For example, they might need to be used on young children, carried around constantly by the user, or they might even need to be used in a military combat situation.
One of the stress tests we conduct to assess whether a device is sufficiently robust is a freefall (drop) test. The expectation is that most devices must either be obviously broken or function as expected following the freefall impact (or impacts). At Team Consulting, our custom-made freefall test rig, designed and built in-house, supports freefall testing of different device types, sizes and shapes. To operate it, the rig is positioned at the required height and the device is inserted into the grippers. The pneumatic system holds the device in place at the required release orientation. With the flick of a switch, the device is released in a non-turbulent way to impact a rigid test surface.
Conducting these tests can help us answer several questions during the product design and development phases, such as:
- Is the device susceptible to damage from a drop? Is the damage detectable, and will it be obvious to the user when it is broken?
- Are any function-critical components broken or misaligned when dropped?
- Does a device function correctly after it has been dropped?
A helpful piece of equipment that we use at Team to gain further insight into freefall testing is a high-speed camera. Typically, the human eye can see between 30 and 60 frames per second, but this is not enough to acquire the data we need. I have recently been using a high-speed camera to record footage at 15,000 frames per second, allowing a much greater insight into exactly what occurs during testing, particularly at the point of impact. To make sure we can view every aspect of the device during the freefall test, during investigatory testing we can also use custom made clear components to allow us to see through the entire device. This means we can ensure that no detail or issue is left hidden.
Alongside drop testing, we can also use the high speed camera to see frame by frame how a device functions. For example, we can examine how an auto-injector functions when activated into phantom limbs, as well as through different types of clothing, in order to determine just how much pressure is needed in the mechanism.
During filming, the micro-movements of the device components can be analysed to determine their overall travel distance, as well as if they have become misaligned or if there is any damage during freefall. It’s fascinating to be able to view device functions that usually happen too quickly for the human eye to detect. It brings a whole new level of detail to device testing.
The amount of data and information that you can collect using a high-speed camera really is incredible. These tests provide us with valuable data to use and compare to different moulded components, so we can confirm the best solution for the device to ensure robustness of its design.