homogeneous membranes are disclosed which are composed of acrylic copolymers and are capable of absorbing 10 % to 50 % of their dry weight of water . the copolymers include a hydrophilic component which comprises acrylic esters having a poly substituent as part of the alcohol moiety . the copolymers further comprise methacrylate and / or acrylate monomer units . the membranes are useful in the fabrication of biosensors , e . g ., a glucose sensor , intended for in vivo use . variations in the ratios of the monomeric components make possible the fabrication of membranes which have varying permeabilities .