Fabrication and development of magnetically actuated PDMS micropump for drug delivery

Abstract

Micropump is an essential component used in drug delivery systems to dispense small amounts of liquid into human body in a controlled manner over a period of time. Polydimethylsiloxane (PDMS) is an elastomeric polymer with attractive properties such as non-toxicity, biocompatibility and blood compatibility. Further, its bio-inertness inhibits microbial growth, thereby making it more attractive for biomedical applications. This paper presents the fabrication of a simple, dual-chamber, valveless PDMS micropump with an integrated magnetic actuator for drug delivery applications. The micropump developed in the laboratory consisted of two circular reservoirs provided with end nozzle diffusers. The reservoirs were sealed with a thin PDMS layer and a permanent magnet was attached over it to form the actuation membrane. An external magnet fixed to a rotating DC motor shaft is used to excite the actuation membrane. The magnetic force of attraction and repulsion between the rotating magnet and membrane magnet resulted in a vibrating diaphragm and consequently aids in pumping action. The liquid flow rate through the PDMS micropump depends on the rotational speed of the motor, viscosity of the liquid and the geometry of the micropump. Exhaustive experimental results were obtained with different viscous fluids such as water, ethanol and coconut oil. For these fluids, the motor speeds of the developed PDMS micropump worked satisfactorily. The parameter of interest such as flow rate for water was found to be 1.7 mL/min at a motor speed of 3000 rpm. The highest flow rate of the pump corresponded to the resonant frequency of the actuation membrane which is 14.8 Hz.