An optical modality to sense a fluid by exploiting Dyakonov-Tamm (DT) waves was devised. In the modality, the
fluid is present on both sides of the guiding interface. Theory showed that the angular location of reflectance dip
in a practically implementable configuration will shift if the refractive index of the fluid changes. Furthermore,
the detection sensitivity will decrease as the refractive index of the fluid increases over a wide range, and
should be comparable to that for sensing modalities that exploit surface-plasmon-polariton (SPP) waves. Higher
sensitivities are available with DT waves than with SPP waves, and the DT-wave-based sensor should be simpler
to fabricate than the SPP-wave-based sensor. Multiple DT waves are excitable at the same frequency, leading
to multiple channels for more reliable sensing as well as for sensing multiple analytes simultaneously.