Here, we demonstrate a completely 3D printed flow sensor that operates on the principle of Joule heating and hot wire anemometry. Finite element modeling with experimentally determined properties of the fused deposition modeling filaments was used to confirm the feasibility of such a sensor. Steady-state simulations were used to calculate the operating voltage that produces the maximum sensitivity while keeping the wire temperature 10 °C below the glass transition temperature. At this operation voltage, the transient simulations indicated a response time of 10 s (>95 % of the change in resistance) and a flow sensitivity of −2.33 Ω/sccm, or a relative change in resistivity of 0.036 per sccm. The flow sensor was realized through fused deposition modeling of a combination of electrically conductive and non-conductive filaments. A proof of concept was demonstrated by simultaneously recording infrared images and measuring the change in resistance of the sensor. Experimentally, higher operation voltage (12−15 V) was required compared to the simulations. At 12 V, the flow sensitivity ranged from 0.014 to 0.032 per sccm, whereas at 15 V, it ranged from 0.039 to 0.065 per sccm. The completely 3D printed flow sensors hold potential to be used as an alternate to existing range of flow sensors, more prominently, manufacturing on-demand and integrating with product packaging.
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