Forget the tatoos, forget about pricks, forget about pain. The future is to use low cost BIOCATALYTIC CONDUCTING traces capable to be placed on the skin with ball-point pens that contain enzymes capable to react with the desired analyt wither glucose (i.e. glucose oxidase), pollutants as phenols (i.e. tyrosinase) etc…
Do not forget that to make conductive inks with carbon is very easy to do (DIY).
A wide spectrum of possibilities inside healthcare, environmental and defense fields.