Issue link: https://www.e-digitaleditions.com/i/1543258
Inhalation February 2026 31 is force ensures that the gate only opens when the patient generates sufficient pressure to properly actu- ate the inhaler and deliver the medication effectively. a * (1.225 kg/m 3 3 * 0.000008 m 3 ) = 1.20 N Equation 3: Calculating the force from acceleration and mass. Experimental setup To assess the effectiveness of our adaptor device in enhancing inspiratory flow rates, measurements of flow rate were conducted with and without the device. e experimental setup consisted of a vari- able transformer, manometer, tubing, prototype and a BIOPAC data acquisition system (BIOPAC Sys- tems Inc., Goleta, California, United States). e BIOPAC system was configured and integrated into the testing rig to facilitate accurate data collection. Baseline flow rates were recorded by adjusting the variable transformer to activate the vacuum system then measuring the flow without the adaptor. e adaptor device was then attached to the BIOPAC sen- sor and both the flow rate and pressure buildup were recorded. In instances where the gate did not open automatically due to insufficient pressure buildup, it was manually opened and the resulting flow rate was documented for comparison. Computational fluid dynamics (CFD) modeling To further understand the movement of medication particles through our proposed device, computa- tional fluid dynamics (CFD) modeling was utilized. e simulations were conducted using COMSOL Multiphysics simulation software (COMSOL Inc., Burlington, Massachusetts, United States) to evalu- ate airflow patterns, pressure distribution and particle trajectories within the adaptor. e DPI and adaptor geometry were imported into the software and a fine mesh was applied to capture intricate flow character- istics. Airflow rates were simulated across a range of inspiratory conditions (25-60 L/min) to mimic pedi- atric usage. To account for detailed fluid behavior under these conditions, laminar compressible flows were assumed. e governing equations—and defi- nitions of their symbols—for CFD of laminar com- pressible flows are: ρ ∂u + ρ(u∙∇)u = ∇∙[-p2I + K ] + F ∂t ∂ρ + ∇∙(ρu) = 0 ∂t K = µ(∇u + (∇u) T ) - 2 µ(∇∙u)I 3 tasteless. To mitigate this problem, the FlowMate device utilizes a unique feedback mechanism that provides both visual and auditory feedback to con- firm the actuation of the system. An indicator but- ton will pop upwards when a sufficient pressure gradient has been generated to allow medication to flow through, thus acting as the visual indicator. e auditory indicator is the sound of the gate swing- ing upward to hit the indicator button. is feed- back mechanism can provide patients with peace of mind, knowing they have successfully received the prescribed dose of medication. Governing principles Pressure plays a critical role in generating the air- flow necessary to inhale medication from the Ellipta and other DPIs. To calculate the force required to open the gate in our proposed device, we assume that the pressure gradient resulting from inhalation is just sufficient to release the maximum dosage of medication. Once this gradient is achieved, the gate opens mechanically to allow the medication to be delivered effectively. e fundamental equation that governs our device's operation is the pressure-gradient force equation (Equation 1). In this equation, ρ represents fluid density, dP is the pressure difference, and dz is the distance. When a pressure difference exists, airflow is accelerated as it moves from areas of high pressure to low pressure. a = -1 dP ρ dz Equation1: Pressure-gradient force. Using Equation 1, we calculated the pressure in the system (Equation 2). For this, we used the density of air, 1.225 kg/m ³ . Research on DPIs shows that the Ellipta requires 5-10 mbar of pressure for actu- ation, as it is classified as a medium-resistance DPI [19] Converting 5 mbar to Pascals gives 500 Pa and we determined the gate's width to be approxi- mately 0.0008 m. a = -1 × 500 pascal 1.225 kg/m 3 0.0008 m Equation 2: Pressure-gradient force with substituted variables. Next, using Equation 3, we calculated the pressure- gradient force. Starting with the acceleration derived in Equation 2, we calculated the mass of air moving across the gate. is required determining the air's volume in the chamber (0.000008 m ³ ) and multi- plying it by the air density to obtain the air mass. By multiplying this mass with the acceleration, we determined the force required for the gate to open.