measured as disclosed herein examples of analytes or biological components of interest are known and include such well known analytes of clinical significance as glucose hemoglobin lipids cholesterol protein etc other analytes will be readily apparent to those skilled in the art a more detailed illustration of two embodiments of the invention are shown in fig2 a and 2b the self actuated pump 12 is located either within the shoe fig2 a or in an insert fig2 b and is operated by the downward force exerted by the subject 39 s foot 40 during normal walking in both embodiments the sensing unit 16 is fastened to the subject 39 s leg 26 in the embodiment shown in fig2 a the device of the invention is partially housed inside a shoe 38 the pneumatic assembly comprises a self actuated pump 12 located inside shoe 38 in the region directly below the heel of the subject 39 s foot 40 the self actuated pump 12 includes a diaphragm 22 two check valves 32 and 34 and a cavity 28 the first check valve 34 oriented to allow the passage of gas or fluid into the cavity 28 is connected via pneumatic conduit 18 to the sensing unit 16 which is attached to the subject 39 s leg 36 by means of a fastening means 26 in this embodiment the fastening means is shown as a cuff a second check valve 32 is oriented to allow the passage of gas or fluid out of the cavity 28 in operation of this embodiment the mechanical motion of the subject 39 s body in this case the force applied by the subject 39 s foot 40 while walking provides mechanical.