Micropumps for Lab-on-Chip Applications

Introduction

Microfluidics is a multidisciplinary field which deals with manipulation of fluids at micro and nanoscale. Microfluidic systems can be used to develop portable and affordable diagnostic devices, such as microfluidic chips or lab-on-a-chip (LOC) devices, for applications such as disease diagnosis, drug screening, and environmental monitoring. Microfluidic systems are capable of handling small volumes of fluid with high precision, which is particularly useful for applications that require accurate dosing, mixing, and analysis. In general, a microfluidic system consists of a network of microchannels, reservoirs, inlet ports for injecting fluids, outlet port for removing fluids, micromixers, micropumps, microvalves and an integrated sensor system for analytical studies. Integration of these components makes miniaturization of diagnostic systems with multiple sensors known as Lab-On-Chip (LOC). Micropumps are required to pump the fluids between the reservoirs and the microfluidic chip, inside the microfluidic chip from one zone to another zone and then finally to send the fluid to the waste collecting reservoirs. There is a delay in realizing the commercialization of microfluidic systems due to lack of reliable microfluidic components especially micropumps and microvalves. These micropumps may be of mechanical or non-mechanical actuator type based on the principle of working and these will be discussed in detail in this chapter.

A micropump is a miniaturized pump that is capable of delivering small volumes of fluids typically in the picolitre or nanolitre range, with high precision and accuracy. Micropumps are being developed for use in a wide range of applications, including drug delivery, medical diagnosis, chemical analysis, and microfluidic systems (Karthikeyan et al. 2023). There are several types of micropumps, including mechanical, piezoelectric, electrokinetic, and thermopneumatic, each with its unique characteristics and advantages. Mechanical micropumps use moving parts to generate flow, while piezoelectric micropumps use mechanical vibrations to create pressure changes in the fluid. Electrokinetic micropumps employ the electric field to create fluid flow, and thermopneumatic micropumps use thermal expansion to generate pressure gradients. The choice of micropump type depends on the specific application and the desired performance criteria.

Figure 1.

Classification of micropumps

Overall, micropumps represent an exciting and rapidly developing technology with significant potential for a wide range of applications. Micropumps can be classified based on various factors, such as their pumping mechanism, fluid handling capabilities, and application areas. Here are a few common classification schemes for micropumps as shown in Figure 1. Micropumps are important in drug delivery uses because they allow for the exact movement of medicine from a reservoir to the target location. The micropumps are fabricated using Micro Electro Mechanical Systems (MEMS) technology and are highly suitable for wearable and implantable drug delivery systems for the management of chronic illnesses as well as the efficient discharge of insulin for diabetic patients.