Design and analysis of microfluidic cell counter using spice simulation

Abstract

Microfluidic cytometers based on coulter principle have recently shown a great potential for point of care biosensors for medical diagnostics. In this study, the design and characterization of coulter based microfluidic cytometer are investigated through electrical circuit simulations considering an equivalent electrical model for the biological cell. We explore the effects related to microelectrode dimensions, microfluidic detection volume, suspension medium, size/morphology of the target cells, and, the impedance of the external readout circuit, on the output response of the sensor. We show that the effect of microelectrodes' surface area and the dielectric properties of the suspension medium should be carefully considered when characterizing the output response of the sensor. In particular, the area of the microelectrodes can have a significant effect on cell's electrical opacity (the ratio of cell impedance at high to low frequency) which is commonly used to distinguish between sub-populations of the target cells (e.g. lymphocytes vs. monocytes when counting white blood cells). Moreover, we highlight that the opacity response vs. frequency can significantly vary based upon whether the absolute cell impedance or the differential output impedance is used in its calculation. These insights could provide valuable guidelines for the design and characterization of coulter based microfluidic sensors.

Thin flexible lab-on-a-film for impedimetric sensing in biomedical applications

“…The measured amplitude is a good representation of the cell size passing through biochip 78 – 80 . Due to cell passage between electrodes, the impedance change is recorded as a unipolar pulse ~ V A , and V B via Wheatstone bridge circuit with resistances, R b of 47 kΩ 81 . Both pulses (V A and V B ) are fed to the input of the lock-in amplifier, which takes the differential to remove the common mode noise between them and generate a bipolar pulse for each cell passing through the electrode on the plotter (see Fig.…”

Advances in healthcare wearable devices

“…Body secretions like sweat, saliva, tears, and urine contain important biomarkers that are essential for monitoring and diagnostic purposes. HWDs can be used directly or through their integration with other platforms, for example, microfluidic platforms can be integrated for the extraction of useful information from different biofluids 79 . Microfluidic platforms of different materials can be used in HWDs for example, polymer-based microfluidic devices, paper-based microfluidic devices, and microsized needles known as microneedles 80,81 .…”

A wearable telehealth system for the monitoring of parameters related to heart failure

“…Both solutions are not only expensive but also have surgical risks [ 5 ]. Most of the commercially available devices are not in accordance with the World Health Organization's (WHO) ASSURED criteria for Affordable, Sensitive, Specific, User-friendly, Rapid and robust, Equipment-free and Deliverable devices [ [12] , [13] , [14] ]. Therefore, there is a need for a non-invasive solution that can provide continuous and real-time monitoring of parameters related to HF.…”