Holographic sensor

A sensor for detecting the presence or measuring the concentration of a target analyte, the sensor comprising:

• (i) a first phase comprising a first crosslinked polymer;
• (ii) a second phase comprising a second crosslinked polymer;
• and
• (iii) a target analyte recognition agent;
• the first phase and second phase arranged to form an optical grating;
• wherein the first crosslinked polymer is obtained by polymerising a prepolymer composition comprising 1 mol % or less of a crosslinking agent by mol of the prepolymer composition.

A method for making a sensor for detecting the presence or measuring the concentration of a target analyte, the method comprising:

• (i) polymerising a first prepolymer composition comprising 1 mol % or less of a crosslinking agent by mol of the first prepolymer composition to form a first phase comprising a first crosslinked polymer;
• (ii) introducing a second prepolymer composition into the first phase;
• and
• (iii) polymerising the second prepolymer composition to form a second phase comprising a second crosslinked polymer such that an optical grating is formed by the first and second phases;
• wherein one of the first and second crosslinked polymers comprises a target analyte recognition agent.