In this report, a polymer-filled porous silicon (pSi) structure is described that is able to detect changes in temperature around a critical value en route to developing a temperature sensor deployed in wounds dressings that signals inflammation or infection of the wound bed. Using surface-initiated atom transfer radical polymerization (SI-ATRP), thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) chains are grafted onto pSi layers with different porosity and pore size and the optical changes (effective optical thickness below and above the lower critical solution temperature (LCST)) are monitored via interferometric reflectance spectroscopy. Six etching conditions and three different surface functionalization conditions are explored in order to optimise the optical response to temperature change. Thermally oxidised pSi samples with the highest investigated porosity (80%) show the largest optical response and will be the target for developing optical sensors of wound temperature.