Comparative Study and Simulation of Capacitive Sensors in Microfluidic Channels for Sensitive Red Blood Cell...

Area of Science:

• Microfluidics
• Biosensing
• Biomedical Engineering

Background:

• Lab-on-a-chip (LOC) devices integrate analytical processes on a single platform.
• Interdigital capacitive (IDC) sensors are utilized in microfluidic systems for particle detection.
• Red blood cells (RBCs) are critical bioparticles for detection in various applications.

Purpose of the Study:

• To comparatively analyze the detection sensitivities of 1D, 2D, and 3D capacitive sensors for RBCs in microfluidic channels.
• To propose a novel 3D parallel plate capacitance (PPC) sensor structure for enhanced RBC detection.
• To evaluate the performance of different capacitive sensor designs in a microfluidic environment.

Main Methods:

• Simulations were performed using COMSOL Multiphysics® v5.5 to determine sensor detection sensitivities.
• A 25 μm × 25 μm PDMS microfluidic channel was used with simulated RBCs (5-10 μm).
• Conformal mapping was employed to translate 1D IDC sensor dimensions to equivalent 2D/3D PPC sensor dimensions.

Main Results:

• The study determined the detection sensitivity of 1D, 2D, and 3D capacitive sensors for RBCs.
• Proposed 2D and 3D PPC sensors demonstrated a 3× to 20× improvement in sensitivity over 1D IDC sensors.
• A capacitance difference of 100 aF was achieved for healthy RBC detection with the proposed 3D sensor.

Conclusions:

• Advanced capacitive sensor designs (2D and 3D) offer significantly improved sensitivity for RBC detection in microfluidic systems.
• The novel 3D PPC sensor structure shows promise for high-resolution bioparticle detection.
• Capacitive sensing in microfluidics provides a viable platform for sensitive and efficient biological analysis.