A GMR-based Magnetic Flow Cytometer Using Matched Filtering - - PowerPoint PPT Presentation

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A GMR-based Magnetic Flow Cytometer Using Matched Filtering - - PowerPoint PPT Presentation

Sep 10, 2022 162 likes •349 views

A GMR-based Magnetic Flow Cytometer Using Matched Filtering Chih-Cheng Huang, Xiahan Zhou, Da Ying, and Drew A. Hall University of California, San Diego Optical Flow Cytometer Quantitative cellular analysis in hematology Identifying

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A GMR-based Magnetic Flow Cytometer Using Matched Filtering

Chih-Cheng Huang, Xiahan Zhou, Da Ying, and Drew A. Hall University of California, San Diego

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Optical Flow Cytometer

  • Quantitative cellular analysis in hematology
  • Identifying prognostic indicators:
  • Cancer, HIV, and other time-dependent biomarkers
  • Gold standard for multi-parametric analysis
  • Sophisticated instrumentation

Challenge: Hard to translate to a PoC setting!

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Magnetic Flow Cytometer

Signal [mΩ] Blood Sample MNPs

MNP-coated cells evoke change of sensor resistance

Hz

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Optical FCM

  • Complex optics, lasers, and

photodetectors

  • Extensive sample preparation
  • Long turnaround times and
  • ut of reach for routine

monitoring

Magnetic FCM

  • Biological samples have no

magnetic background

  • Sample preparation can

largely be eliminated

  • Can be miniaturized, which

also improves their sensitivity

Optical- vs. Magnetic-FCM

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Multi-stripe Layout

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Single-strip

Unique signature improves matched filtering

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  • Commonly used inside hard disk drives
  • Key enabler for higher areal density (larger HDD)
  • Nobel prize in 2007 awarded to Fert and Grünberg

Magnetoresistive Sensors

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R.S. Gaster, D.A. Hall, S.X. Wang nanoLetters 2011 (cover art)

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Parallel State

GMR Spin-Valves (GMR SV)

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Bias Point (90˚) 𝑁𝑆 = 𝑆𝐵𝑄 − 𝑆𝑄 𝑆𝑄 Parallel (0˚) Antiparallel (180˚)

D.A. Hall, R.S. Gaster, et al. - Biosensors and Bioelectronics 2010

Hext

Antiparallel State

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System Architecture

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Inlet Outlet

120µm

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Micromagnetic Simulations

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5,000× Adembeads

Simulations closely match with our measurement results!

Random distribution of MNPs on a cell

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Hydrodynamic Analysis

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Magnetic force DLVO force Gravity Hydrodynamic force Langevin force Magnetic force

Particle diameter (m) Forces (N)

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M450 M280 MyOne Adem Nanomag SHS30 MACS

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Micromagnetic Simulation of MNPs

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Y: signal ratio (R/Redge-peak) (Height/Diameter)

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ToF Measurement Results

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Detection of individual magnetic bead (M-450)

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Matched Filtering

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Improve detection of signal events and reject false alarms Minimum detectable SNR:14 dB  4.5 dB

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Flow Rate Optimization

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10 20 30 40 50 10 20 30 40

Detected Events Pumping rate (L/min)

10 20 30 40 50 20 40 60 80 100 120

Maximum Signal (m) Pumping rate (L/min)

Tradeoff between signal and flow rate for a given Hz

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Complex Detection

15 MNPs MNPs Biotin-coated Polymer Beads

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Measurement of Real Cells

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Detection of pancreatic cancer cells

20μm

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  • Multi-stripe layout: enables distinct magnetic

signature used for matched filtering

  • Matched filter: reduces minimum detectable SNR

from 14 dB to 4.5 dB, and improves detection efficiency

  • ToF measurements: offers multi-parametric

analysis of flowing analytes

  • GMR-based FCMs: increases portability and rapid

“sample-to-answer” measurement capability

Conclusion

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Thanks!

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