Planar fluidic channels on TiO2 nanoparticle coated paperboard (original) (raw)

Enhancing Capillary-Driven Flow for Paper-Based Microfluidic Channels

ACS Applied Materials & Interfaces, 2016

Paper-based microfluidic devices have received considerable interest due to their benefits with regards to low manufacturing costs, simplicity and the wide scope of applications. However, limitations including sample retention in paper matrix and evaporation as well as low liquid flow rates have often been overlooked. This paper presents a paper-based capillary-driven flow system that speeds up flow rates by utilizing narrow gap geometry between two parallel surfaces separated by a spacer. The top surface is hydrophobic while the bottom surface is a hydrophobic paper substrate with a microfluidic channel defined by a hydrophilic pathway, leaving sides of the channel open to air. The liquid flows on the hydrophilic path in the gap without spreading onto the hydrophobic regions. The closed channel flow system showed higher spreading distances and accelerated liquid flow. An average flow rate increase of 200% and 100% was obtained for the nanoparticle coated paperboard and the blotting papers used, respectively. Fast liquid delivery to detection zones or reaction implies rapid results from analytical devices. In addition, liquid drying and evaporation can be reduced in the proposed closed channel system.

A comparative study of paper-based microfluidic devices with respect to channel geometry

Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2016

h i g h l i g h t s • Comparative study is done by using wax printing and photolithography in paper fluidics format from a hydrodynamic point of view. • Channel boundary drag results in a reduced flow rate below 4-5 mm channel width. • Contact angle, permeability and porosity values are calculated for flow of oleic acid in the paper. • A mathematical model is derived from Washburn equation that includes this drag effect and tortuous flow path. • Adding circular obstacles in a square grid formation and changing their density in the channel can vary the flow velocity of fluid depending on the tortuous flow path.

Controlling capillary-driven surface flow on a paper-based microfluidic channel

Microfluidics and Nanofluidics, 2016

This paper describes two methods for controlling capillary-driven liquid flow on microfluidic channels. Unlike flow driven by external forces, capillary-driven flow is dominated by interfacial phenomena and, therefore, is sensitive to the channel geometry and chemical composition (surface energy) along the channel. The first method to control fluid flow is based on altering surface energy along the channel through regulation of UV irradiation time, which enables adjusting the contact angle along the fluid path. The slowing down (delay) of the liquid flow depends on the stripe length and its position in the channel. Using this technique, we generated flow delays spanning from a second to over 3 min. In the second approach, we manipulated the flow velocity by introducing contractions and expansions in the channel. The methods used herein are inexpensive and can be incorporated to the microfluidic channel fabrication step. They are capable of controlling liquid flow with precise time delays without introducing the foreign matter in the fluidic device.

Compressibility of porous TiO2 nanoparticle coating on paperboard

Nanoscale Research Letters, 2013

Compressibility of liquid flame spray-deposited porous TiO2 nanoparticle coating was studied on paperboard samples using a traditional calendering technique in which the paperboard is compressed between a metal and polymer roll. Surface superhydrophobicity is lost due to a smoothening effect when the number of successive calendering cycles is increased. Field emission scanning electron microscope surface and cross‒sectional images support the atomic force microscope roughness analysis that shows a significant compressibility of the deposited TiO2 nanoparticle coating with decrease in the surface roughness and nanoscale porosity under external pressure. PACS 61.46.-w; 68.08.Bc; 81.07.-b

Fluid flow in a microfluidic paper-based porous substrate by capillary action

Paper has a porous structure, and fluid imbibition in a paper channel is possible passively through the hydrophilic surfaces by capillary action, so it can be an appropriate substrate in the field of microfluidics. To realize the fluid behavior in a paper-based microchannel, there is a need to obtain a model for fluid flow. In this study, the capillary-driven flow in a porous structure was simulated, and the effect of geometrical and physical parameters on the wetted length and average fluid pressure was investigated. Geometric parameters are pores’ shape and size, channel dimensions, and porosity, while the investigated physical parameters were the contact angle, surface tension coefficient, and viscosity. According to the results, geometric parameters influenced the capillary pressure through the capillary surface and channel resistance variation, and physical parameters directly impacted the capillary pressure. Considering the wetted length results, the fluid imbibition velocity ...

Fabrication of micro/nano fluidic channels by nanoimprint lithography and bonding using SU-8

Microelectronic Engineering, 2009

Polymer-based micro/nano fluidic devices are becoming increasingly important for biological applications and fluidic control. In this article, we report and demonstrate a novel fabrication process for micro/nano fluidic channels based on nanoimprint lithography (NIL) and bonding using SU-8, which is an excellent material for micro/nano fluidics application due to its good chemical stability, bio-compatibility and optical properties. Bonding pressure and temperature were found to be essential to the bonding strength and channel profile control. This fabrication technique has great potential for low-cost mass production of SU-8 based micro/nano fluidic devices.

Wettability behavior of nanotubular TiO2

2016

intended for biomedical applications Molhabilidade de nanotubos de TiO2 para aplicações biomédicas La humectabilidad de nanotubos de TiO2 para aplicaciones biomédicas