Sample Preparation In Microstructured Devices

Abstract

Handling and processing of μl and sub-μl sized samples are challenging, and have a series of attendant problems, such as loss of sample on the walls of transfer devices, loss by evaporation, loss of components of the sample during manipulation and processing, and obtaining a representative sample from an nonhomogeneous specimen. A further difficulty is that the expected concentration of the analyte restricts the scale of miniaturization of the sample. Detection of rare cell types (e.g., cancerous cells, fetal cells in maternal circulation, assessment of minimal residual disease) and microorganisms is problematic, and the expected cell frequency or microbial load will determine a sample size compatible with detection. In such cases a specific selection or a preconcentration step is a more logical approach to ensure the presence of the desired cells or microorganisms. In this review the principles and applications of the current range of microfluidic (e.g., pumps, valves) and microfiltration systems (e.g., silicon microfilters) and electronically controlled microstructured devices relevant to the micro-sample preparation are critically discussed.