Comprehensive characterization of a microfluidic platform for DEP manipulation and bio-impedance detection using multi-sized polystyrene microbeads
Authors: Sherif Sameh , Ghallab Yehya H. , Ismail Yehea 
Published: January 2025

Abstract
Dielectrophoresis (DEP) manipulation combined with micro-electric impedance spectroscopy (µEIS) presents a sophisticated approach for cellular analysis and dielectric characterization. While conventional cell analysis techniques rely on complex labeling methods with inherent limitations, integrating DEP and µEIS offers non-invasive, label-free cellular characterization with enhanced sensitivity. This study presents an innovative dual-mode DEP platform incorporating both levitation (LEVDEP) and rotational (ROTDEP) forces, integrated with high-precision impedance measurement capabilities on one chip, enabling simultaneous Cell controlling and manipulation and dielectric signature extraction within a single microfluidic device. The fabricated and developed microfluidic platform demonstrated exceptional particle discrimination through the dual mode, with distinct responses for both particle populations. Under

$$F_{lEV.DEP}^{10.4 \mu m}$$

F

l
E
V
.
D
E
P

10.4
μ
m

2.01 MHz showed a 63.4% magnitude increase, while

$$F_{lEV.DEP}^{24.9 \mu m }$$

F

l
E
V
.
D
E
P

24.9
μ
m

, particles exhibited a higher 81.2% increase at the same force, yielding a 2.48 × enhancement in discrimination ratio compared to no-DEP conditions. ROTDEP at 110 kHz induced even more pronounced differences, with

$$F_{ROT.DEP}^{10.4 \mu m}$$

F

R
O
T
.
D
E
P

10.4
μ
m

showing a 120% magnitude increase (phase patterns: −24.501° to −34.363°) and

$$F_{ROT.DEP}^{24.9 \mu m}$$

F

R
O
T
.
D
E
P

24.9
μ
m

µm particles demonstrating a 145% increase (phase patterns: −31.267° to −42.891°), achieving a 3.16 × discrimination ratio enhancement. The impedance spectrum revealed distinct frequency-dependent signatures, with ROTDEP showing superior mid-frequency discrimination (10.4 µm: 1.9370×

$${10}^{4}$$

10

4

Ω vs 24.9 µm: 2.0542×

$${10}^{4}$$

10

4

Ω at 110 kHz) and LEVDEP optimizing high-frequency characterization (10.4 µm: 1.6677×

$${10}^{4}$$

10

4

Ω vs 24.9 µm: 1.5849×

$${10}^{4}$$

10

4

Ω at 2.01 MHz). These signatures demonstrate the platform’s comprehensive particle characterization capabilities through complementary DEP forces. The dual-mode approach enhanced discrimination ratios by 2.48 × under

$$Lev. force$$

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v
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f
o
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c
e

and 3.16 × under

$$LEV. force$$

L
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f
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c
e

at selected characteristic frequency range compared to

$$NonDEP force$$

NonDEPforce

conditions. Comprehensive impedance analysis through frequency spectrum (10 kHz—2.01 MHz) revealed unique frequency-dependent cell signatures,

$$ROT. force$$

R
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f
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c
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demonstrating superior mid-frequency discrimination (magnitude differences of 1.9370 × 104 Ω vs 2.0542 × 104 Ω at 110 kHz) and LEVDEP optimizing high-frequency characterization (1.6677 × 104 Ω vs 1.5849 × 104 Ω at 2.01 MHz). Impedance dielectric analysis conducted over the 10 kHz to 2.01 MHz frequency range demonstrated frequency-dependent characteristics for each selected cell population. ROTDEP enhanced the discrimination in the mid-frequency range (110 kHz), with 10.4 µm particles presenting impedance magnitudes of 1.9370 × 104 Ω, while 24.9 µm particles displayed 2.0542 × 104 Ω, yielding a distinct separation ratio of 1.06 × . In the high-frequency domain (2.01 MHz), LEVDEP optimized particle characterization revealed that 10.4 µm particles exhibited a resistance of 1.6677 × 104 Ω. In contrast, 24.9 µm particles showed a resistance of 1.5849 × 104 Ω, resulting in a separation ratio of 1.05 × . The dual-mode approach markedly improved discrimination capabilities, with LEVDEP demonstrating a 2.48 × enhancement and ROTDEP exhibiting a 3.16 × increase in separation ratios relative to no-DEP conditions. This proposed dual-force implementation exhibited notable efficacy in designated frequency ranges: ROTDEP excelled in mid-frequency discrimination, achieving magnitude differences of 11.72 × 103 Ω between particle populations, whereas LEVDEP optimized high-frequency characterization with differences of 8.28 × 103 Ω, facilitating comprehensive particle discrimination through complementary DEP forces. This study establishes a novel microfluidic platform integrating dual-mode DEP manipulation with high-sensitivity dielectric features impedance detection, achieving a 163.1% enhancement in signal-to-noise SNR ratio compared to the conventional impedance mode. The proposed system demonstrates exceptional particle discrimination capabilities, with LEVDEP achieving a 63.4% and 81.2% magnitude increase for 10.4 µm and 24.9 µm particles, respectively, at 2.01 MHz. In comparison, ROTDEP induced more pronounced increases of 120% and 145% at 110 kHz. The proposed system significantly improved discrimination ratios (2.48 × under LEVDEP and 3.16 × under ROTDEP) relative to no-DEP conditions, identifying clear phase behavior patterns for both particle populations. Impedance analysis over the 10 kHz to 2.01 MHz frequency range identified distinct frequency-dependent characteristics. ROTDEP exhibited enhanced mid-frequency discrimination, measuring 1.9370 × 104 Ω compared to 2.0542 × 104 Ω, while LEVDEP provided optimized high-frequency characterization, with values of 1.6677 × 104 Ω versus 1.5849 × 104 Ω. This system, which is label-free and non-invasive, facilitates cellular dielectric analysis with improved throughput and measurement precision. It provides substantial benefits for biological research, medical diagnostics, and drug analysis and development through its dual-force implementation and extensive impedance characterization capabilities.