Design and Simulation of a Medium Voltage Micropump for Blood Flow in a Microchannels System E. Gonzalez a, H. Baez a, F. Hernandez b, H. Mendoza-Leon b, M. Ramirez a National Polytechnic Institute – Computing Research Center, Mexico City, 07738, Mexico. Center of Nanoscience and Micro and Nanotechnology of IPN, Mexico City, 07738, Mexico. Email:
[email protected]
a b
Keywords: Micropump, microchannels, PDMS, comb drive, simulation, blood flow. Nowadays, the development of applications for clinical diagnosis is rapidly growing up and, parallel to this, the implementation of Lab on Chips (LOCs) is an important task to be achieved. The separation of elements of blood is one of the topics that have been studied in recent years [1, 2]. Different techniques have been employed to promote de flux of a fluid in a microchannels system, since those using capillarity or mechanical principles to the ones using a magnetic effect [3]. In this work, the design of a peristaltic micropump to promote the flux of blood into a microchannels system is presented. The micropump is designed for medium voltage bias (20-30 v), it uses three membranes in its structure and is proposed to be fabricated with PDMS, which is widely used in microfluidic systems [4, 5]. This micropump is fabricated with smaller dimensions than others of the same type [6, 7], the main applications are those to dose fluids or medical drugs. When exposed to high temperature, the blood loses its properties and cells are damaged [2], for this reason it is necessary to avoid to use of high voltages.
[1] Yuta Nakashima, Sakiko Hata, Takashi Yasuda; Blood plasma separation and extraction from a minute amount of blood using dielectrophoretic and capillary forces; Sensors and Actuators B 145 (2010) 561–569. [2] Xing Chen, Da Fu Cui, Chang Chun Liu, Hui Li; Microfluidic chip for blood cell separation an d collection based on crossflow filtration; Sensors and Actuators B 130 (2008) 216–221. [3] Eui-Gyu Kim, Jae-geun Oh, Bumkyoo Choi; A study on the development of a continuous peristaltic micropump using magnetic fluids; Sensors and Actuators A 128 (2006) 43–51. [4] Jessamine Ng Lee, Xingyu Jiang, Declan Ryan, and George M. Whitesides; Compatibility of Mammalian Cells on Surfaces of Poly (dimethylsiloxane); Langmuir 2004, 20, 11684-11691. [5] Santiago Alvarado, S. Vázquez–Montiel; Propiedades físico-químicas de membranas PDMS empleadas en lentes líquidas; Superficies y Vacío 22(3) 61-66, septiembre de 2009. [6] M. Shen, L. Dovat, M.A.M. Gijs; Magnetic active-valve micropump actuated by a rotating magnetic assembly; Sensors and Actuators B 154 (2011) 52–58. [7] Ling-Sheng Jang &Wai-Hong Kan; Peristaltic piezoelectric micropump system for biomedical applications; Biomed Microdevices (2007) 9:619–626.
Figure 1. Schematic diagram.
Figure 2. Mechanical simulation of the membrane.
Figure 3. Operation sequence of micropump.
Figure 4. Simulation of fluid (blood).
The design presented here uses a comb drive actuator whit electrostatic principle to generate movement en the three membranes. The design considers that the heat induced from the comb drive is not in direct contact with the micropump. With this design we expect to solve the problem of heating. Figure 1 shows a schematic diagram of all parts that integrate the device; microchannels system, comb drive, inlet, outlet and the micropump. Simulations were done to validate the operation of the micropump. These simulations were to know the maximum displacement of the membrane, also to know the movement and acceleration of fluid in the microchannels when the membrane is moving. Figure 2 shows the results of displacement when a force is applied in the membrane. The applied force was 1µN and the maximum displacement of the membrane was 29.18 µm. The micropump was simulated with its complete structure. Figure 3 shows the operation sequence of micropump. Figure 4 shows the simulation of fluid flow, when the force is applied in the membrane. Cases when one or two membranes are activated were considered. For the mechanical simulation PDMS is considered as structural material and for flow simulation the blood is considered as fluid, as shown in Table 1.
Table 1. Simulation parameters.
The comb drive actuator was selected such that it has a force of 1µN; figure 5 shows some considerations for the design.
Young´s modulus 500e3[Pa] Density 1060[kg/m^3]
Figure 5. Actuator analysis.
Material: PDMS. Poisson´s ratio Density 0.49999 0.97[kg/m^3] Material: Blood. Dynamic viscosity 0.0027Pa*s
