A plain linked list consists of one anchor and one end pointer, which points to the last element of the linked list.
So you'll need two variables. Here's a possible setup:
SensorBlock *Anchor = NULL, *EndPtr = Anchor;
if(!Anchor) EndPtr = Anchor = new SensorBlock(s); //Assuming that you have a constructor, which takes this parameter.
else EndPtr = EndPtr->LLelement = new SensorBlock(s);
This code first checks, whether the anchor is already set or not. If it isn't, the anchor is instantiated and the EndPtr is set to Anchor. Otherwise, it is 'appended' to the list by creating a new SensorBlock element, which is then assigned to 'EndPtr->LLelement' and finally to EndPtr itself.
Be careful to release the dynamically allocated SensorBlock elements once you're done with them and if you delete any element, be sure to update ALL references, which point to it. (Anchor, EndPtr, LLelement of previous element). Otherwise you'll break your chain and destroy the list.