▁the ▁por os ity ▁of ▁por ous ▁sil icon ▁is ▁varied ▁depending ▁on ▁its ▁potential ▁application ▁areas . ▁ ▁P ore ▁size ▁The ▁por os ity ▁value ▁of ▁sil icon ▁is ▁a ▁macro scop ic ▁parameter ▁and ▁doesn ’ t ▁yield ▁any ▁information ▁regarding ▁the ▁micro structure ▁of ▁the ▁layer . ▁It ▁is ▁proposed ▁that ▁the ▁properties ▁of ▁a ▁sample ▁are ▁more ▁accur ately ▁predicted ▁if ▁the ▁p ore ▁size ▁and ▁its ▁distribution ▁within ▁the ▁sample ▁can ▁be ▁obtained . ▁Therefore , ▁por ous ▁sil icon ▁has ▁been ▁divided ▁into ▁three ▁categories ▁based ▁on ▁the ▁size ▁of ▁its ▁por es ; ▁mac rop orous , ▁mes op orous , ▁and ▁mic rop orous . ▁ ▁Key ▁characteristic ▁of ▁por ous ▁sil icon ▁ ▁High ly ▁cont roll able ▁properties ▁ ▁Por ous ▁sil icon ▁studies ▁conducted ▁in ▁ 1 9 9 5 ▁showed ▁that ▁the ▁behavior ▁of ▁por ous ▁sil icon ▁can ▁be ▁alter ed ▁in ▁between ▁" bio - in ert ", ▁" bio active " ▁and ▁" res orb able " ▁by ▁varying ▁the ▁por os ity ▁of ▁the ▁sil icon ▁sample . ▁The ▁in - v it ro ▁study ▁used ▁sim ulated ▁body ▁fluid ▁containing ▁ion ▁concentration ▁similar ▁to ▁the ▁human ▁blood ▁and ▁tested ▁the ▁activities ▁of ▁por ous ▁sil icon ▁sample ▁when ▁exposed ▁to ▁the ▁flu ids ▁for ▁prolong ed ▁period ▁of ▁time . ▁It ▁was ▁found ▁that ▁high ▁por os ity ▁mes op orous ▁layers ▁were ▁completely ▁removed ▁by ▁the ▁sim ulated ▁body ▁flu ids ▁within ▁a ▁day