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In this paper we study the gas sensing performance of a compact silicon photonics Mach-Zehnder interferometer (MZI) with a coiled sensing arm. A partially exposed sensor was fabricated using deep UV lithography, with a process resolution of 248 nm. Testing with inert gases, He and N 2 , resulted in a measured sensitivity and limit of detection of ∼1458 nm/RIU and ∼8.5×10 -5 RIU, respectively, in a sensing volume of 1.852 picoliters. The temperature sensitivity of the sensor was 166 pm/ • C and the inclusion of a cladded ring-resonator, post-MZI, allowed resolving the temperature drift due to gas flow. In order to further enhance the overlap of the optical mode with the measurand and thus the sensitivity, a suspended MZI was designed and simulated with an expected sensitivity of ∼5500 nm/RIU, for wavelengths around 1550 nm and a temperature of 300 K.

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In this study, deoxyribonucleic acid (DNA) hybridization was demonstrated using a suspended silicon photonics micro-ring resonator with a 90 nm-thick slab and morpholino as the capture probe. Complementary DNA of various concentrations were tested achieving a surface sensitivity of 2.12 nm/nM, a detection limit of 250 pM, and an intrinsic detection limit of 36.9 pM. A bulk sensitivity of 98 nm/RIU and an intrinsic detection limit of 1.03 × 10 −3 RIU was also measured upon exposure to isopropanol/deionized water solutions. With these characteristics, the suspended 90 nm slab ring sensor proved as a promising candidate for lab-on-a-chip bio-sensing applications.