Why test in liquid
Hydrogels, cartilage, tissues and many polymers are defined by their water content; measured dry, they are effectively different materials. Medical devices, implants and their coatings work immersed in body fluids, and many industrial coatings and seals work in liquids. Testing in the liquid keeps the material in its real state and the contact in its real environment.
How the module works
The sample sits in a liquid cup, designed to suit the sample, and stays immersed throughout the test. The indenter or stylus works through the liquid. The liquid can be heated from room temperature up to 60 °C. The same nanoindentation, scratch and friction tests run as in air, with the liquid changing only the environment, not the method.
Testing soft, hydrated materials
Very soft hydrated materials need adapted test conditions. In NANOVEA’s hydrogel study, a 3 mm spherical tip at 10 mN measured ~42 µm of creep in 70 s, and the initial contact was complicated by surface tension pulling the ball into the gel before load registered. Large tips, low loads and careful contact analysis make such measurements reliable.
Medical devices and biomaterials
Device materials are best compared in the fluid they will meet. NANOVEA compared silicone and polyether-polyurethane pacing-lead insulation in Hanks’ solution: low-load friction at 50 mN, then wear, with the silicone showing a wear scar about twice as wide (~1.2 mm vs ~0.6 mm).
