Gas sensors are important in many fields such as environmental monitoring, agricultural production, public safety, and medical diagnostics. Herein, tamm plasmon resonance in a photonic bandgap is used to develop an optical gas sensor with high performance. the structure of the proposed sensor comprises a gas cavity sandwiched between a one-dimensional porous silicon photonic crystal and an Ag layer deposited on a prism. the optimised structure of the proposed sensor achieves ultra-high sensitivity (S = 1.9×10 5 nm/RiU) and a low detection limit (DL = 1.4×10 −7 RiU) compared to the existing gas sensor. the brilliant sensing performance and simple design of the proposed structure make our device highly suitable for use as a sensor in a variety of biomedical and industrial applications. Gas sensing has different applications in many fields such as the food industry, medicine, safety, environment, agriculture, and cosmetic 1,2. For example, the detection of volatile organic compounds such as acetone and toluene in exhaled breath is used as a biomarker for many diseases 3,4. In addition, the determination of the concentration of harmful gases such as CO 2 and N 2 O can be applied as an environmental pollution monitor 5. Currently, optical gas sensors are of great interest to researchers because they do not require complicated radioactive/fluorescent labels 6,7. Surface plasmon resonance, Tamm plasmon (TP) resonance, waveguide, and photonic crystal are all examples of platforms for optical sensing 8-12. Photonic crystals (PCs) are useful for a wide range of biomedical and environmental sensing applications. This is due to an impressive set of relevant properties, such as ultrahigh sensitivity, low detection limit, and fast response time 13,14. PC refers to a range of materials characterised by a periodic refractive index along one, two, or three dimensions (1DPC, 2DPC, or 3DPC, respectively). The propagation of electromagnetic waves in PCs can be controlled because of the photonic bandgap (PBG) 15-17. 1DPCs are more appropriate for most applications, given their low cost and ease of fabrication compared to 2DPCs and 3DPCs 18. Recently, PCs have been widely used in various sensor systems. A high-precision gas index sensor, which was proposed by Jágerská et al., reached a sensitivity of 510 nm/RIU based on a PC air-slot cavity 19. Hua-Jun studied a surface plasmon resonance nanocavity antenna array for use as a gas sensor with a high sensitivity of 3200 nm/RIU 20. Wang et al. suggested a guided-mode resonance gas sensor with a sensitivity as high as 748 nm/ RIU 21. Pevec and Donlagic designed a fiber-optic Fabry-Perot gas sensor with a sensitivity of 1550 nm/RIU 22. García-Rupérez et al. presented a highly sensitive device for antibody detection using the slow light regime of a PC waveguide 23. Chen et al. designed a PC/Ag/graphene structure to function as a refractive index sensor based on the Tamm state, with a numerical sensitivity of 1178.6 nm/RIU 24. Auguié et al. studied TP resonance at the interface between a meta...

Photonic sensing is a novel technology and accurate measurement for biosensing applications. The present work proposes a defective one-dimensional photonic crystal (1D-PC) based on Si/SiO2-layers with a central liquid-filled defect layer as a blood sugar concentration biosensor in the visible region. The transmission spectrum is calculated numerically by using the transfer matrix method. The thickness of the defect layer and incident angle are optimized to achieve the best performance of the sensor. The results show that the localization of defect mode shifts to a longer wavelength with increasing the defect layer thickness. In addition to increasing the incident angle from θ0 = 0° to θ0 = 90°, the defect peak was shifted towards the short wavelength region. The optimized value of our structure demonstrates high sensitivity for the blood sugar (S = 1100 nm/RIU) in the range of concentration 0–500 mg dl−1, more enhancement of the quality factor (3.539 × 106) and very low limit of detection (8.8 × 10−9 RIU) are achieved. Our results indicate that the proposed structure has higher performance as a blood sugar sensor than many previously reported data. Besides, the simplicity of the proposed structure makes it favorable to the industrial design using inexpensive and massive product nanofabrication techniques.

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In this manuscript, we have explored the photonic biosensing application of the 1D photonic crystal (PhC) (AB)NCDC(AB)N, which is capable of detecting reproductive progesterone and estradiol hormones of different concentration levels in blood samples of females. The proposed structure is composed of an air cavity surrounded by two buffer layers of material MgF2, which is sandwiched between two identical 1D sub PhCs (AB)N. Both sub PhCs are made up of alternate layers of materials, SiO2 and Si, of period 5. MATLAB software has been used to obtain transmission characteristics of the structure corresponding TE wave, only with the help of the transfer matrix method. The mainstay of this research is focused on the dependence of the intensity and position of the defect mode inside the photonic bandgap with respect to reproductive hormone concentrations in blood samples, change in the thickness of the cavity region and change in angle of incidence corresponding to TE wave only. The proposed design shows high sensitivity of 98.92 nm/nmol/L and 96.58 nm/nmol/L when the cavity of a thickness of 340 nm is loaded with progesterone and estradiol hormones of concentrations of 80 nmol/L and 11 nmol/L, respectively, at an incident angle of 20°. Apart from sensitivity, other parameters such as quality factor and figure of merit have also been computed to gain deep insight about the sensing capabilities of the proposed design. These findings may pave the path for the design and development of various sensing devices capable of detecting gynecological problems pertaining to reproductive hormones in females. Thus, the simple design and excellent performance makes our design most efficient and suitable for sensing applications in industrial and biomedical fields.