A novel integrated dual microneedle-microfluidic impedance flow cytometry for cells detection in suspensions

Abstract

In this study, a new, simple and cost-effective impedance detection of yeast cell concentration by using a novel integrated dual microneedle-microfluidic impedance flow cytometry was introduced. The reported method for impedance flow cytometry detection utilizes embedded electrode and probe in the microfluidic device to perform measurement of electrical impedance when a presence of cells at sensing area. Nonetheless, this method requires costly and complicatedly fabrication process of electrode. Furthermore, to reuse the fabricated electrode, it also requires intensive and tedious cleaning process. Due to that, a dual microneedle integrated at the half height of the microchannel for cell detection as well as for electrical measurement was demonstrated. A commercial available Tungsten needle was utilized as a dual microneedle. The microneedle was easy to be removed from the disposable PDMS microchannel and can be reused with the simple cleaning process, such as washed by using ultrasonic cleaning. Although this device was low cost, it preserves the core functionality of the sensor, which is capable of detecting the passing cells at sensing area. Therefore, this device is suitable for low cost medical and food safety screening and testing process in developing countries.

An impedance flow cytometry with integrated dual microneedle for electrical properties characterization of single cell

“…Both clean PDMS microchannels were pre-heat on a hot plate for 5 minutes at a temperature of 120˚. After pre-heat, both PDMS microchannels were treated with oxygen plasma (Plasma EtchPE-25, Plasma Etch, Inc., Carson City, NV, USA) for 25 seconds with oxygen at 10 cc/min to improve adhesion strength [29].…”

“…The Tungsten microneedle is reusable and quite easy to clean. Two Tungsten microneedles were located between the top and bottom of the disposable microchannel to sense and measure the impedance of cells flowing through an applied electric field [28,29]. The concept of facing electrodes configuration has been used because this approach generates a more homogeneous electric field distribution (but not perfectly uniform) and is more sensitive due to the electric field being restricted into a smaller detecting volume [10,30].…”

Numerical Investigation of a Novel Wiring Scheme Enabling Simple and Accurate Impedance Cytometry

“…Microfluidic impedance cytometry is a label-free technique for analysing single particles and cells at high throughput [ 1 , 2 ]. It is used in different biological assays, including particle sizing and counting, cell phenotyping, and disease diagnostics (e.g., [ 3 , 4 , 5 , 6 ]). In a typical impedance chip, suspended particles flow through a microchannel and two electrode pairs are used to measure the variation in channel impedance induced by the passage of a particle.…”