Metamaterial Terahertz Sensor for Measuring Thermal-Induced Denaturation Temperature of Insulin

Abstract

A terahertz (THz) metamaterial biosensor is proposed to measure the thermal induced denaturation temperature of the insulin, a typical protein. The unit cell of the biosensor consists of a H-shaped metal structure enclosed by a U-shaped metal structure on a 500- $\mu \text{m}$ -thick high resistance silicon substrate. The metamaterial THz biosensor has high sensitivity of 85 GHz/RIU (Refractive Index Unit). The sample is fabricated using a surface micromachining process and characterized by a THz time-domain spectroscopy (TDS) system, using the insulin solution as analyte. Experimental results show that the sensor is very sensitive to the change of the insulin concentration, and the detectable concentration as low as 0.05 IU (Insulin Unit)/ $\mu \text{l}$ . In the experiment, three different concentrations of the insulin are used as the analytes and a temperature controllable heater is used to induce the denaturation of the insulin. The experimental results show that the denaturation starts from 70 °C and completes at about 88°C, and these two temperatures are independent of the initial concentrations of the insulin. The proposed biosensor has small size and high sensitivity, which are very useful for biological detection.