A novel optofluidic sensor that measures the local pressure of the fluid inside a microfluidic channel is presented. It can be integrated directly on-channel and requires no additional layers in fabrication. The detection can be accomplished at a single wavelength; and thereby, only a single laser diode and a single photodetector are required. This renders the sensor to be compact, cheap and easy to fabricate. Basically, the sensor consisted of a Fabry–Pérot microresonator enclosing the fluidic channel. A novel structure of the Fabry–Pérot was employed to achieve high-quality factor, that was essential to facilitate the single wavelength detection. The enhanced performance was attributed to the curved mirrors and cylindrical lenses used to avoid light diffraction loss. The presented sensor was fabricated and tested with deionized water liquid and shown to exhibit a sensitivity up to 12.46 dBm/bar, and a detection limit of 8.2 mbar. Numerical simulations are also presented to evaluate the mechanical–fluidic performance of the device.

This work reports a theoretical investigation of the effect of Joule heating and temperature‐dependent zeta potential on the electroosmotic flow measurements in calorimetric flow sensing. Joule heating resulting from the applied electric field in electroosmotic flow increases the temperature of the liquid inside the sensor and, consequently, modifies the sensor performance. The model presented in this paper considers temperature dependence of the wall zeta potential on the sensor characteristics. Additionally, all liquid properties such as density, viscosity, relative permittivity, specific heat, thermal conductivity, and electrical conductivity are taken as temperature‐dependent properties. A comparison between the characteristics of the modelled sensor in the presence and absence of Joule heating is presented. The effect of heater power on sensor characteristics is also discussed. Simulation results reveal that Joule heating and temperature dependence of zeta potential have a significant effect on the behaviour of calorimetric flow sensors, which must be considered when this type of sensor is used to measure electroosmotic flow. Temperature dependence of zeta potential, in particular, affected the velocity distribution inside the sensor considerably.