In this work, structurally chiral medium (SCM) based biosensors for the detection of blood plasma are designed and theoretically investigated. To do that, the SCM with the 42m point group symmetry is considered. The introduced structure is irradiated with circularly polarized light. A photonic bandgap is observed in the transmission and reflection spectrum, which represents the circular Bragg phenomenon. The sensor consists of a sample layer located between two identical SCMs. Sensor performance is evaluated using a transfer matrix method (TMM). The results show that the defect mode is sensitive to any changes in the refractive index of the defect layer when the defect layer is infiltrated with different samples of blood plasma. We show a sensitivity of 108.88 nm/RIU when the applied sample thickness is 700 nm. The proposed structure is compact in size, easy to build, cost-effective. And it can provide real-time blood plasma biosensors.
