near mirror 380 fig3 d shows the reader unit 310 scanning an implant while the user 360 is watching television 390 fig3 e shows the systematic tracking of the iop of a research mouse 365 by a plurality of reader units 310 a and 310 b the position and orientation of the head of mice are very predictable and thus suitable for iop sensing by reader units 310 a and 310 b when consuming water or food in one embodiment the collected iop data is matched with the specific animal sensed in this case mouse 365 through the use of implanted electronic id tags thus a single iop detection device such as reader unit 310 b can be used to monitor a whole group of animals fig4 a b illustrate a small scale implantable pressure sensor 400 according to an embodiment of the invention the sensor 400 comprises two pressure responding flexible mechanical structures in this case pressure sensitive bilayer membrane disks 439 a 439 b embedded with a plurality of nanophotonic components 437 whose reflection spectrum varies as the geometry of the hosting structure changes in a predictable way as a function of iop nanophotonic components 437 may be nanoparticles and or nano patterns having a pitch p and diameter d in this embodiment force resisting mechanical flexures.