title: Label-free whole blood cell differentiation based on multiple frequency AC impedance and light scattering analysis in a micro flow cytometer.
abstract: We developed a microfluidic sensor for label-free flow cytometric cell differentiation by combined multiple AC electrical impedance and light scattering analysis. The measured signals are correlated to cell volume, membrane capacity and optical properties of single cells. For an improved signal to noise ratio, the microfluidic sensor incorporates two electrode pairs for differential impedance detection. One-dimensional sheath flow focusing was implemented, which allows single particle analysis at kHz count rates. Various monodisperse particles and differentiation of leukocytes in haemolysed samples served to benchmark the microdevice applying combined AC impedance and side scatter analyses. In what follows, we demonstrate that AC impedance measurements at selected frequencies allow label-free discrimination of platelets, erythrocytes, monocytes, granulocytes and lymphocytes in whole blood samples involving dilution only. Immunofluorescence staining was applied to validate the results of the label-free cell analysis. Reliable differentiation and enumeration of cells in whole blood by AC impedance detection have the potential to support medical diagnosis for patients with haemolysis resistant erythrocytes or abnormally sensitive leucocytes, i.e. for patients suffering from anaemia or leukaemia.
authors.affiliation: Physikalisch-Technische Bundesanstalt (PTB), Abbestrasse 2-12, 10587 Berlin, Germany. joerg.neukammer@ptb.de.
authors.forename: Peter
authors.initials: P
authors.lastname: Simon
authors.forename: Marcin
authors.initials: M
authors.lastname: Frankowski
authors.forename: Nicole
authors.initials: N
authors.lastname: Bock
authors.forename: Jörg
authors.initials: J
authors.lastname: Neukammer
mesh_terms: D001772:Blood Cell Count / Q000295:instrumentation / Q000379:methods; D001792:Blood Platelets / Q000166:cytology; D002454:Cell Differentiation; D000067493:Dynamic Light Scattering / Q000295:instrumentation / Q000379:methods*; D017097:Electric Impedance; D004566:Electrodes; D004912:Erythrocytes / Q000166:cytology*; D005434:Flow Cytometry / Q000295:instrumentation*; D006461:Hemolysis; D006801:Humans; D056656:Lab-On-A-Chip Devices; D007962:Leukocytes / Q000166:cytology*; D057230:Limit of Detection; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation; D059629:Signal-To-Noise Ratio