*Proceeding Paper* **Effect of Storage Reservoir on Fluid Velocity in Lateral Flow Paper Device †**

**Hamza Abbas, Mubashar Ali, Nauman Naeem, Hammas Ullah, Moazzam Ali and Ali Turab Jafry \***

Faculty of Mechanical Engineering, Ghulam Ishaq Khan Institute of Engineering Sciences and Technology, Topi 23460, Pakistan; gme2223@giki.edu.pk (H.A.); gme2187@giki.edu.pk (M.A.); gme2331@giki.edu.pk (N.N.); hammas.ullah@giki.edu.pk (H.U.); gme2330@giki.edu.pk (M.A.)

**\*** Correspondence: ali.turab@giki.edu.pk

† Presented at the Third International Conference on Advances in Mechanical Engineering 2023 (ICAME-23), Islamabad, Pakistan, 24 August 2023.

**Abstract:** Paper-based microfluidics provides a versatile platform for numerous applications, including diagnostics at the point of care, environmental detection, and food quality control. Utilizing paper as a substrate offers numerous benefits, including flexibility, biodegradability, low cost, and capillary-driven flow. Despite significant advancements in paper-based microfluidic devices, regulating fluid flow effectively within the paper channel remains a persistent challenge. In order to resolve this problem, our research proposes a method for manipulating fluid flow in the paper channel by altering the surface contact between the storage medium and the paper channel. According to the results, increasing the contact area between the reservoir and the paper surface decreases the flow velocity and increases the fluidic time delay. This is due to the increased diffusion area between the storage medium and the paper channel, which creates resistance to liquid flow. Therefore, the liquid takes longer to travel through the paper channel, resulting in a decrease in velocity relative to contact areas of 50% or 70%. We are confident that this method of flow control can enable lateral flow sensing devices with enhanced flow variation options for use in medical, environmental, or food quality applications.

**Keywords:** microfluidics; paper-based microfluidics; contact area; flow control; reservoirs
