2. Different types of ligands

Most sensors use ligands inspired by nature. The use of a biological compound gives the biosensor a high degree of specificity. The most commonly used ligands are enzymes and antibodies. But whole cells, cellular organelles, nucleic acids, antigens or even receptors for biologically active molecules (hormones, toxins, growth factors, neurotransmitters...) can also be used. In fact, any biological molecule can be used to specifically analyze the desired "analyte". This is known as analyte "recognition".

Fixed biological compounds can be divided into two categories: those which simply bind the analyte without modification, such as antibodies and receptors, and those with catalytic activity, such as enzymes and micro-organisms. The former present a reversibility problem, which confines them to discontinuous measurements, interspersed with a surface regeneration step....