Patent ID: 7964414

Claim:
A biosensor which comprises a substrate having at least two types of surfaces on a single plane, wherein at least one type of said surfaces retains a physiologically active substance and at least one other type of said surfaces does not retain a physiologically active substance, and wherein at least two types of hydrophilic compounds with different molecular weights are covalently bound to a self-assembling film or a hydrophobic polymer layer on said surface that does not retain the physiologically active substance, wherein said hydrophilic compounds are represented by NH 2 —(CH 2 CH 2 O) n —CH 2 CH 2 OH, wherein the average molecular weight of a hydrophilic compound with the smallest molecular weight is between 100 and 1,000, and wherein the average molecular weight of a hydrophilic compound with the largest molecular weight is between 1,000 and 1,000,000.