Open AccessA portable optical reader and wall projector towards enumeration of bio-conjugated beads or cells
Author(s) -
Macdara Glynn,
David J. Kinahan,
Niamh A. McArdle,
Jane L. Kendlin,
Tríona M. O׳Connell,
Jens Ducrée
Publication year - 2017
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0189923
Subject(s) - inverted microscope , lab on a chip , chip , microfluidics , optical microscope , materials science , microscope , microfluidic chip , nanotechnology , optoelectronics , lens (geology) , biomedical engineering , computer hardware , optics , computer science , scanning electron microscope , physics , composite material , telecommunications , medicine
Measurement of the height of a packed column of cells or beads, which can be direclty related to the number of cells or beads present in a chamber, is an important step in a number of diagnostic assays. For example, haematocrit measurements may rapidly identify anemia or polycthemia. Recently, user-friendly and cost-efficient Lab-on-a-Chip devices have been developed towards isolating and counting cell sub-populations for diagnostic purposes. In this work, we present a low-cost optical module for estimating the filling level of packed magnetic beads within a Lab-on-a-Chip device. The module is compatible with a previously introduced, disposable microfluidic chip for rapid determination of CD4+ cell counts. The device is a simple optical microscope module is manufactured by 3D printing. An objective lens directly interrogates the height of packed beads which are efficiently isolated on the finger-actuated chip. Optionally, an inexpensive, battery-powered Light Emitting Diode may project a shadow of the microfluidic chip at approximately 50-fold magnification onto a nearby surface. The reader is calibrated with the filling levels of known concentrations of paramagnetic beads within the finger actuated chip. Results in direct and projector mode are compared to measurements from a conventional, inverted white-light microscope. All three read-out methods indicate a maximum variation of 6.5% between methods.