Development of a novel electro-osmotic pump

• Main Author: Wang, Jianbin.
• Other Authors: Yang Chun, Charles
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Mechanical engineering::Fluid mechanics
• Online Access: http://hdl.handle.net/10356/53970
• Institution: Nanyang Technological University

Electro-osmotic flow micropump offers the advantage of a pulse free bi-directional flow as opposed to mechanical pumps where moving parts such as actuators are need. Also, because of the concept of electro-osmosis which requires just an electric field to cause fluid motion would enable the pump design to be simple and easy for fabrication. The design of a prototype of a pump using PMMA material as the housing with its channel packed with 125µm glass fibres has been presented. Initial packing procedure was time-consuming. It was difficult to achieve a close packing as glass fibres were inserted strand by strand. A flow sensor was used to determine the performance of the glass fibres based electro-osmotic pump. It is a very accurate method as human errors are minimized. Different magnitude of electric-field was applied across the pump to produce flow rates showing a linearly proportionate relation. The results of the glass fibres able electro-osmotic pump was compared with the previous pump packed with 30-50µm glass beads. Flow rates up to 96.8µL/min were achieved at the beginning. Surface treatment was done to improve the surface charge density of the glass fibres. The fibres were treated with acetone, isopropyl alcohol and sodium hydroxide. Compact packing was done using a shrink tube to improve the electro-osmotic flow of the pump. More fibres were able to fit into the channel holder increase the total surface area of glass in the channel holder. This also allowed the removal of the frits required to keep the fibres from escaping simplifying the manufacturing process of the micropump. The pump was able to produce a maximum of 196.4µL/min with all the improvements done. The maximum operating time of the micropump was found to be 48.5mins. The problem of joule heating as well as electrolysis effect in channel might cause the performance of the pump to deteriorate.