In fluidic systems, it is often desirable to collect samples in the hydrated state at one location. Most methods devised to do this are often complex. In this work, we present a method that uses a simple squeeze flow. We demonstrate its use in the collection of cells (algal cells), particulates (microbeads and fluorescent nanobeads) and non-particulates (EGFP). This fluidic system is amenable for high content microscopy. An assumption often made is that objects being observed are fixed spatially and are sufficiently populated. Without the ability to collect, this can lead to the need for searching through multiple field of views (FOVs). We report that the generation of a squeeze flow by the circular coverslip onto a liquid sample allows for objects to be acquired at the rim regions of the circular coverslip. By using a coverslip of 13 mm diameter and sample volumes between 2 μL and 4 μL, the coverslip was completely filled without any excess flow beyond its outer rim. Furthermore, sample compression speeds between 100 μm/s and 1000 μm/s did not change the effect of the object collection outcome. A comparison was made between manually placing the coverslip on the liquid sample by hand and using a motorised translator to generate the squeeze flow and in both cases, similar outcomes were obtained. Quantitative measurements and image analysis confirmed that all the objects investigated had been displaced and relocated at the rim regions of the coverslip at a very high degree and ready to be collected. Also by using a metal cylinder and probe tip, pre-concentration of material was achieved.

Date Published: 7 December 2013
PDF: 12 pages
Proc. SPIE 8923, Micro/Nano Materials, Devices, and Systems, 89230U (7 December 2013); doi: 10.1117/12.2033733

Published in SPIE Proceedings Vol. 8923:
Micro/Nano Materials, Devices, and Systems
James Friend; H. Hoe Tan, Editor(s)