The sensitivity of a recently proposed spike detector exploiting the volatile properties of memristive device is optimised. A 200 nm × 200 nm TiOx memristive device in volatile region is biased with sub-threshold, unipolar and bipolar neural events. The input neural signal is pre-processed using different amplification settings. The resistive state response of the test device in response to the input events is analysed and it is found that inclusion of events in positive polarity leads to subsequent increase in the number of false events when benchmarked against state-of-the-art spike detector (template matching system). The performance of the system is thereafter optimised by determining optimum amplification settings and employing an offset such that positive polarity events in the input signal are minimised.