Limits...
A microfluidic device based on an evaporation-driven micropump.

Nie C, Frijns AJ, Mandamparambil R, den Toonder JM - Biomed Microdevices (2015)

Bottom Line: Typical results show that with 1 to 61 pores (diameter = 250 μm, pitch = 500 μm) flow rates of 7.3 × 10(-3) to 1.2 × 10(-1) μL/min are achieved.The results are theoretically analyzed using an evaporation model that includes an evaporation correction factor.The theoretical and experimental results are in good agreement.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands.

ABSTRACT
In this paper we introduce a microfluidic device ultimately to be applied as a wearable sweat sensor. We show proof-of-principle of the microfluidic functions of the device, namely fluid collection and continuous fluid flow pumping. A filter-paper based layer, that eventually will form the interface between the device and the skin, is used to collect the fluid (e.g., sweat) and enter this into the microfluidic device. A controllable evaporation driven pump is used to drive a continuous fluid flow through a microfluidic channel and over a sensing area. The key element of the pump is a micro-porous membrane mounted at the channel outlet, such that a pore array with a regular hexagonal arrangement is realized through which the fluid evaporates, which drives the flow within the channel. The system is completely fabricated on flexible polyethylene terephthalate (PET) foils, which can be the backbone material for flexible electronics applications, such that it is compatible with volume production approaches like Roll-to-Roll technology. The evaporation rate can be controlled by varying the outlet geometry and the temperature. The generated flows are analyzed experimentally using Particle Tracking Velocimetry (PTV). Typical results show that with 1 to 61 pores (diameter = 250 μm, pitch = 500 μm) flow rates of 7.3 × 10(-3) to 1.2 × 10(-1) μL/min are achieved. When the surface temperature is increased by 9.4°C, the flow rate is increased by 130 %. The results are theoretically analyzed using an evaporation model that includes an evaporation correction factor. The theoretical and experimental results are in good agreement.

No MeSH data available.


(a) Schematic of our proposed device, with a filter paper base for fluid collection, a microchannel that connects the inlet to a sensing cavity and then to the channel outlet cavity that is covered by a porous structure through which the fluid evaporates. (b) Simplified device, without filter paper and sensing cavity, which was used to quantitatively characterize the evaporative pumping behavior. (c) Schematic of the pore array at the evaporation end. (d) Real device that was used for flow rate characterization, compared with a 5 Eurocent coin
© Copyright Policy - OpenAccess
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4372687&req=5

Fig1: (a) Schematic of our proposed device, with a filter paper base for fluid collection, a microchannel that connects the inlet to a sensing cavity and then to the channel outlet cavity that is covered by a porous structure through which the fluid evaporates. (b) Simplified device, without filter paper and sensing cavity, which was used to quantitatively characterize the evaporative pumping behavior. (c) Schematic of the pore array at the evaporation end. (d) Real device that was used for flow rate characterization, compared with a 5 Eurocent coin

Mentions: A schematic of our proposed microfluidic device is shown in Fig. 1a. Green layers in Fig. 1a are PET foils coated on both sides by an adhesive film, allowing for straightforward lamination. Filter paper (VWR 313, cut by CO2 laser VLS 3.5, Universal Laser Systems, yellow in Fig. 1a) is stuck onto the backside of the adhesive PET layer stack (white in Fig. 1a). The filter paper, cut in a square grid of lines with a width and spacing of 4 mm and 1 mm respectively, collects sweat from the skin surface, and transports the liquid to the inlet cavity of the microchannel. Two pieces of circular paper are used to fill the inlet cavity to ensure full contact between the liquid and the channel wall. The inlet cavity is connected to a sensing cavity and then to the outlet by microchannels. The sensing cavity can contain for example an electrochemical sensor, which will be integrated in future studies – here we focus on the microfluidics aspects.Fig. 1


A microfluidic device based on an evaporation-driven micropump.

Nie C, Frijns AJ, Mandamparambil R, den Toonder JM - Biomed Microdevices (2015)

(a) Schematic of our proposed device, with a filter paper base for fluid collection, a microchannel that connects the inlet to a sensing cavity and then to the channel outlet cavity that is covered by a porous structure through which the fluid evaporates. (b) Simplified device, without filter paper and sensing cavity, which was used to quantitatively characterize the evaporative pumping behavior. (c) Schematic of the pore array at the evaporation end. (d) Real device that was used for flow rate characterization, compared with a 5 Eurocent coin
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4372687&req=5

Fig1: (a) Schematic of our proposed device, with a filter paper base for fluid collection, a microchannel that connects the inlet to a sensing cavity and then to the channel outlet cavity that is covered by a porous structure through which the fluid evaporates. (b) Simplified device, without filter paper and sensing cavity, which was used to quantitatively characterize the evaporative pumping behavior. (c) Schematic of the pore array at the evaporation end. (d) Real device that was used for flow rate characterization, compared with a 5 Eurocent coin
Mentions: A schematic of our proposed microfluidic device is shown in Fig. 1a. Green layers in Fig. 1a are PET foils coated on both sides by an adhesive film, allowing for straightforward lamination. Filter paper (VWR 313, cut by CO2 laser VLS 3.5, Universal Laser Systems, yellow in Fig. 1a) is stuck onto the backside of the adhesive PET layer stack (white in Fig. 1a). The filter paper, cut in a square grid of lines with a width and spacing of 4 mm and 1 mm respectively, collects sweat from the skin surface, and transports the liquid to the inlet cavity of the microchannel. Two pieces of circular paper are used to fill the inlet cavity to ensure full contact between the liquid and the channel wall. The inlet cavity is connected to a sensing cavity and then to the outlet by microchannels. The sensing cavity can contain for example an electrochemical sensor, which will be integrated in future studies – here we focus on the microfluidics aspects.Fig. 1

Bottom Line: Typical results show that with 1 to 61 pores (diameter = 250 μm, pitch = 500 μm) flow rates of 7.3 × 10(-3) to 1.2 × 10(-1) μL/min are achieved.The results are theoretically analyzed using an evaporation model that includes an evaporation correction factor.The theoretical and experimental results are in good agreement.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands.

ABSTRACT
In this paper we introduce a microfluidic device ultimately to be applied as a wearable sweat sensor. We show proof-of-principle of the microfluidic functions of the device, namely fluid collection and continuous fluid flow pumping. A filter-paper based layer, that eventually will form the interface between the device and the skin, is used to collect the fluid (e.g., sweat) and enter this into the microfluidic device. A controllable evaporation driven pump is used to drive a continuous fluid flow through a microfluidic channel and over a sensing area. The key element of the pump is a micro-porous membrane mounted at the channel outlet, such that a pore array with a regular hexagonal arrangement is realized through which the fluid evaporates, which drives the flow within the channel. The system is completely fabricated on flexible polyethylene terephthalate (PET) foils, which can be the backbone material for flexible electronics applications, such that it is compatible with volume production approaches like Roll-to-Roll technology. The evaporation rate can be controlled by varying the outlet geometry and the temperature. The generated flows are analyzed experimentally using Particle Tracking Velocimetry (PTV). Typical results show that with 1 to 61 pores (diameter = 250 μm, pitch = 500 μm) flow rates of 7.3 × 10(-3) to 1.2 × 10(-1) μL/min are achieved. When the surface temperature is increased by 9.4°C, the flow rate is increased by 130 %. The results are theoretically analyzed using an evaporation model that includes an evaporation correction factor. The theoretical and experimental results are in good agreement.

No MeSH data available.