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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.


Experimental setup for an evaporation driven flow with a heater: The evaporation end of the sample is placed on the heater and the surface temperature rise of the heater is recorded by the thermocouple
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Fig2: Experimental setup for an evaporation driven flow with a heater: The evaporation end of the sample is placed on the heater and the surface temperature rise of the heater is recorded by the thermocouple

Mentions: The evaporation of water in air is enhanced by heating the outlet. A series of experiments is run on a voltage controlled heater (PTC heater, maximum 12 V 3 W from thermo technologies) to investigate the influence of temperature on the evaporation process because of the on-skin applications. The evaporation end of the simplified device is put on the heater to achieve a temperature rise, as shown in Fig. 2. A J-type thermocouple is attached to the heater surface close to the evaporation outlet to record the temperature rise of the heater. The heater is connected to a voltage source to control the power and therefore the temperature on the surface. In the set-up shown in Fig. 2, the heater is not mounted underneath the inlet port in order to prevent extra evaporation at the inlet from influencing the measurement. In the complete device that represents the sweat sensor device (Fig. 1a) the upward facing inlet port is absent, so this additional evaporation is of no concern and the entire device would be heated when attached to the body’s surface.Fig. 2


A microfluidic device based on an evaporation-driven micropump.

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

Experimental setup for an evaporation driven flow with a heater: The evaporation end of the sample is placed on the heater and the surface temperature rise of the heater is recorded by the thermocouple
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig2: Experimental setup for an evaporation driven flow with a heater: The evaporation end of the sample is placed on the heater and the surface temperature rise of the heater is recorded by the thermocouple
Mentions: The evaporation of water in air is enhanced by heating the outlet. A series of experiments is run on a voltage controlled heater (PTC heater, maximum 12 V 3 W from thermo technologies) to investigate the influence of temperature on the evaporation process because of the on-skin applications. The evaporation end of the simplified device is put on the heater to achieve a temperature rise, as shown in Fig. 2. A J-type thermocouple is attached to the heater surface close to the evaporation outlet to record the temperature rise of the heater. The heater is connected to a voltage source to control the power and therefore the temperature on the surface. In the set-up shown in Fig. 2, the heater is not mounted underneath the inlet port in order to prevent extra evaporation at the inlet from influencing the measurement. In the complete device that represents the sweat sensor device (Fig. 1a) the upward facing inlet port is absent, so this additional evaporation is of no concern and the entire device would be heated when attached to the body’s surface.Fig. 2

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.