US-12623220-B2 - Code-multiplexed sensor networks for microfluidic impedance spectroscopy

US12623220B2US 12623220 B2US12623220 B2US 12623220B2US-12623220-B2

Abstract

A microfluidic device for particle analysis, such as immunophenotyping, includes a plurality of microfluidic channels for the passage of a particle-laden fluid flow, a plurality of dedicated impedance sensors for generating impedance signals relative to each microfluidic sensor. The impedance sensors are CODES Coulter sensors, each having a distinct coded sequence for generating mutually orthogonal signals. The system uses a multi-frequency excitation signal for driving the Coulter sensors, such that the Coulter sensors generate multi-frequency impedance signals. The system outputs the multi-frequency signals of the plurality of impedance sensors as a single multi-frequency multiplexed signal, which is subsequently separated into a plurality of single-frequency multiplexed signals, which are then demodulated into single-frequency component signals corresponding to each of the Coulter sensors.

Inventors

Ali Fatih Sarioglu
Ningquan WANG

Assignees

GEORGIA TECH RESEARCH CORPORATION

Dates

Publication Date: 20260512
Application Date: 20191111

Claims (9)

1 . A microfluidic device for particle analysis, comprising: a plurality of microfluidic channels for the passage of a particle-laden fluid flow; a plurality of impedance sensors, each of the plurality of impedance sensors being dedicated to a single microfluidic channel for outputting a signal representative of an impedance across the corresponding microfluidic channel, each of the plurality of impedance sensors comprising a coded sequence of opposing electrode fingers, the coded sequences of the impedance sensors being distinct from one another; and a signal generator in signal communication with the impedance sensors for driving the impedance sensors with an excitation signal, the signal generator being configured to output a multi-frequency excitation signal comprising multiple concurrent tones to each impedance sensor, wherein the impedance sensors are configured in signal communication with the signal generator such that each impedance sensor is driven by the multi-frequency excitation signal with the multiple concurrent tones to generate a multi-frequency signal representative of impedance across the corresponding microfluidic channel, and to output the multi-frequency signals of the plurality of impedance sensors as a single multi-frequency multiplexed signal that comprises each of the multi-frequency signals generated by the individual impedance sensors, and the microfluidic device further comprises: first circuitry programmed to separate the multi-frequency multiplexed signal into multiple single-frequency multiplexed signals, with a separate single-frequency multiplexed signal corresponding to each tone of the multi-frequency excitation signal, and second circuitry programmed to separate each of the single-frequency multiplexed signals to extract single-frequency output signals corresponding to each of the impedance sensors.
2 . The microfluidic device according to claim 1 , wherein the signal generator is configured to output a multi-frequency excitation signal comprising two or more tones, such that each impedance sensor generates a multi-frequency signal representative of an impedance across the corresponding microfluidic channel, the multi-frequency signal generated by each impedance sensor comprising a corresponding number of tones as the excitation signal.
3 . The microfluidic device according to claim 1 , wherein the first circuitry is a lock-in amplifier programmed to receive the multi-frequency multiplexed output signal from the sensor platform, and to separate the multi-frequency multiplexed signal into multiple single-frequency multiplexed signals, with a separate single-frequency multiplexed signal corresponding to each tone of the multi-frequency excitation signal.
4 . The microfluidic device according to claim 1 , wherein the second circuitry is a processing unit programmed to receive separated single-frequency multiplexed signals from the first circuitry, and to separate each of the single-frequency multiplexed signals to extract single-frequency output signals corresponding to each of the impedance sensors.
5 . The microfluidic device according to claim 4 , wherein the processing unit is further programmed to separate single-frequency multiplexed signals to extract component output signals corresponding to individual impedance sensors using a blind signal separation algorithm.
6 . The microfluidic device according to claim 4 , wherein the processing unit is further programmed to separate single-frequency multiplexed signals to extract component output signals corresponding to individual impedance sensors by cross-correlating waveforms of a single-frequency multiplexed signal with pre-defined template waveforms stored in a template library.
7 . The microfluidic device according to claim 1 , wherein the second circuitry is further configured to determine, from the separated component output signals, at least one of a particle size, particle speed, particle elasticity, particle location, and a particle dielectric property.
8 . The microfluidic device according to claim 1 , wherein each of the microfluidic channels comprises an inlet end, an outlet end, and a micro-constriction portion positioned between the input and outlet end, and for each microfluidic channel, the corresponding dedicated impedance sensor is configured to generate a signal representative of impedance at the micro-constriction portion of the corresponding microfluidic channel.
9 . The microfluidic device according to claim 8 , wherein the micro-constriction portion of each microfluidic channel is dimensioned to limit flow therethrough to a particle-by-particle flow.

Description

STATEMENT REGARDING FEDERALLY FUNDED RESEARCH The inventions herein were made with government support under grant no. ECCS 1752170, awarded by the National Science Foundation. The government has certain rights in the inventions. FIELD OF THE INVENTION The present invention relates to apparatuses and methods for flow cytometry. In particular, the present invention is directed to microfluidic sensor platforms and methods of using the same for quantifying physical and chemical properties of microfluidic particles. BACKGROUND OF THE INVENTION Recent developments in microfluidic sensors have made it possible to quantify the physical and chemical properties of individual particles in a particle-laden flow, such as the physical and chemical characteristics of cells in biological assays. In some approaches, a microfluidic particle flow is fed through a microfluidic channel having a micro-constriction that effectively limits the passage of individual particles one at a time, and a microfluidic sensor is used to detect an electrical conduction change within the micro-constriction when a particle passes therethrough. One such microfluidic sensor is a Coulter sensor, which implements resistive pulse sensing (RPS) technology. Coulter sensors are versatile instruments that have been used in analysis of blood cells, proteins, DNA molecules, viruses, and nanoparticles. In the interest of increasing overall throughput of such microfluidic sensors, it has been proposed to construct a multi-sensor chip that provides for individualized particle flow through multiple parallel microfluidic channels, with a dedicated Coulter sensor allocated to each microfluidic channel. It has also been proposed that a multi-sensor chip may output a single multiplexed signal by driving each of the Coulter sensors with separate excitation signals, each having a distinct frequency. However, such approaches significantly increase the complexity of the device, and limit the scalability thereof, as the number of dedicated electrodes and circuits increases linearly with the number of microfluidic channels. Despite the advances provided to date in the art, there remains a need for improvements to microfluidic sensors for yet further advancing the state of the art, and improving the overall throughput and accuracy of such devices and methods generally. SUMMARY OF THE INVENTION A microfluidic device for particle analysis includes a plurality of microfluidic channels for the passage of a particle-laden fluid flow, and a plurality of impedance sensors. Each of the plurality of impedance sensors is dedicated to a single microfluidic channel for outputting a signal representative of an impedance across the corresponding microfluidic channel, and each impedance sensor is provided with a coded sequence of opposing positive and negative electrode fingers, the coded sequences of the impedance sensors being distinct from one another. In some examples the impedance sensors may be coded such that output signals from the plurality of impedance sensors are mutually orthogonal to one another. Each of the microfluidic channels comprises an inlet end, an outlet end, and a micro-constriction portion positioned between the input and outlet end, and the corresponding dedicated impedance sensor for each microfluidic channel is adapted to generate a signal representative of impedance at the micro-constriction portion of the corresponding microfluidic channel. The micro-constriction portion of each microfluidic channel is dimensioned to limit flow therethrough to a particle-by-particle flow. A signal generator is provided for driving the impedance sensors with an excitation signal, the signal generator being adapted to output a multi-frequency excitation signal comprising multiple tones such that the impedance sensors generate multi-frequency signals representative of impedance across the microfluidic channels. The signal generator is adapted to generate multi-frequency signals having two, three, four, or more tones. The microfluidic device comprises a sensor platform for outputting the signals generated by the impedance sensors, and circuitry for processing the output signal. The sensor platform is adapted to output the multi-frequency signals of the plurality of impedance sensors as a single multi-frequency multiplexed signal that comprises each of the coded (e.g., mutually orthogonal) output signals of the impedance sensors. First circuitry, such as a lock-in amplifier, is provided for separating the multi-frequency multiplexed signal into multiple multiplexed signals, with a separate multiplexed signal corresponding to each tone of the multi-frequency excitation signal. Second circuitry, such as a programmed processing unit, is provided for demodulating each of the single-frequency multiplexed signals to extract single-frequency output signals corresponding to each of the impedance sensors. The system is further configured, such as through a programmed processing unit, to