Why does IBIS use LVDT sensors?
LVDT sensors are “linear variable differential transformers” and are essentially inductance displacement sensors. They are inherently linear, and have sub-nanometre resolution. Their performance is very similar to the capacitance sensors used by other manufacturers with one very important exception. LVDT’s are very robust. A capacitive sensor consists of two, and sometimes three, parallel plates. Unfortunately, the plates have to be, by necessity, of very precise geometry, and be positioned very close together. It is common to make these plates from glass, and very common for the plates to break if the indenter shaft, which is connected to the centre or moving plate, is pushed or pulled unintentionally beyond the spacing (less than a mm) of the plates. By contrast, the LVDT sensors used in IBIS are made from stainless steel with a titanium shaft. The centre shaft passes right through the device and so the IBIS nanoindentation head can withstand significant abuse by untrained or inexper
