Sensor for detection

A sensor for determining presence of at least one target molecule in a sample, wherein the sensor comprises:

• i. a layer formed of high aspect ratio molecular structures (HARM-structures), wherein the layer formed of HARM-structures is configured to generate an electrical signal when in contact with signal molecules indicating the presence of the at least one target molecule when an electrical potential is applied to the sensor, wherein the magnitude of the electrical signal correlates with the concentration of the at least one target molecule in the sample;
• and
• ii. a blocking layer on the layer formed of HARM-structures, wherein the blocking layer is formed of a plurality of casein micelles, wherein:
• the casein micelles comprise primary amines, wherein at least part of the primary amines is functionalized with an amine-reactive crosslinker thereby providing at least one linkage group for allowing binding thereto, and
• cavities are formed between the plurality of casein micelles for allowing the signal molecules to diffuse through the blocking layer to the layer formed of HARM-structures such as to generate the electrical signal.