Prediction of Dispersion Rate of Airborne Nanoparticles in a Gas-Liquid Dual-Microchannel Separated by a Porous Membrane: A Numerical Study

Abstract

Recently, there has been increasing attention toward inhaled nanoparticles (NPs) to develop inhalation therapies for diseases associated with the pulmonary system and investigate the toxic effects of hazardous environmental particles on human lung health. Taking advantage of microfluidic technology for cell culture applications, lung-on-a-chip devices with great potential in replicating the lung air-blood barrier (ABB) have opened new research insights in preclinical pathology and therapeutic studies associated with aerosol NPs. However, the air interface in such devices has been largely disregarded, leaving a gap in understanding the NPs' dynamics in lung-on-a-chip devices. Here, we develop a numerical parametric study to provide insights into the dynamic behavior of the airborne NPs in a gas-liquid dual-channel lung-on-a-chip device with a porous membrane separating the channels. We develop a finite element multi-physics model to investigate particle tracing in both air and medium phases to replicate the in vivo conditions. Our model considers the impact of fluid flow and geometrical properties on the distribution, deposition, and translocation of NPs with diameters ranging from 10 nm to 900 nm. Our findings suggest that, compared to the aqueous solution of NPs, the aerosol injection of NPs offers more efficient deposition on the substrate of the air channel and higher translocation to the media channel. Comparative studies against accessible data, as well as an experimental study, verify the accuracy of the present numerical analysis. We propose a strategy to optimize the affecting parameters to control the injection and delivery of aerosol particles into the lung-on-chip device depending on the objectives of biomedical investigations and provide optimized values for some specific cases. Therefore, our study can assist scientists and researchers in complementing their experimental investigation in future preclinical studies on pulmonary pathology associated with inhaled hazardous and toxic environmental particles, as well as therapeutic studies for developing inhalation drug delivery.

Keywords: gas–liquid dual-channel chip; lung-on-a-chip; nanoparticle; numerical simulation; porous membrane.

Figure 1

(a) Air–blood barrier (ABB) in the alveolar space of human lungs; (b) Microfluidic lung-on-a-chip device comprises air/blood channels separated by a thin, porous membrane and two side vacuum channels.

Figure 2

2D model of airborne delivery of NPs into a gas-liquid dual-channel microdevice with a thin, porous membrane.

Figure 3

Comparison of the present numerical results with (a) analytical data in Ref. [31] for a 2D airflow between two parallel plates. Axial fluid velocity and vertical distance from the substrate are normalized with respect to the inlet velocity of 0.3 mm/s and the channel height of 100 µm. Subsequently, (b) numerical data in Ref. [21] is shown for the mean concentration of particles with a diameter of 1 μm along two parallel plates. Distance from the entrance and particle concentration are nondimensionalized, respectively, with respect to a specific length of $3hPe/16$, and initial concentration ($C_0={10}^5/{\mathrm{m}}^2$). $Pe=2\overline{u}h/D$ is the Peclet number, and where $D \left(=2.96\times {10}^{-11 }{\mathrm{m}}^2/\mathrm{s}\right)$ is the diffusion coefficient. Finally, the (c) the numerical result of Ref. [22] for deposition rate of NPs with various diameters on the substrate of an air channel is shown.

Figure 4

(a) Microfluidic device, which is bonded to a glass slide and contains a channel with one inlet and one outlet; (b) Schematic diagram of the fabrication process of the microfluidic device.

Figure 5

Schematic diagram of the experimental setup for injecting the particles into a microfluidic device using a syringe pump and monitoring their dynamics throughout the device with a microscope.

Figure 6

Qualitative comparison of distribution and deposition of the particles on the microchannel substrate obtained from numerical and experimental studies. (a) $d_{\mathrm{p}}=1$ µm, $u_{m,0}=0.03$ mm/s; (b) $d_{\mathrm{p}}=1$ µm, $u_{m,0}=0.1$ mm/s; (c) $d_{\mathrm{p}}=10$ µm, $u_{m,0}=0.1$ mm/s; and (d) $d_{\mathrm{p}}=10$ µm, $u_{m,0}=0.3$ mm/s.

Figure 7

(a) Deposition rate and (b) transfer rate of the media- and air-induced NPs in the top channel of the lung-on-a-chip device when the fluid velocity is 0.3 mm/s, and both pore diameter and pore-to-pore distance are 10 µm.

Figure 8

Deposition rate of airborne NPs of diameter ranging from 10 nm to 900 nm on the substrate of the air channel with different membrane porosities and airflow velocities of (a) 0.3 mm/s and (b) 1 mm/s.

Figure 9

Trajectory of an initially inert 900 nm particle in the porous region for inflow velocities of (a) 0.3 mm/s and (b) 1 mm/s.

Figure 10

Normalized (a) average position and (b) standard deviation of deposited NPs of diameter ranging from 10 nm to 900 on the substrate of the air channel with pore diameter and pore to pore distance of 10 µm under two different fluid velocities of 0.3 mm/s and 1 mm/s. The solid red line corresponds with an ideal deposition.

Figure 11

Snapshots from transient distribution of NPs with a diameter of $900 \mathrm{nm}$ in the lung-on-a-chip device with pore diameter and pore-to-pore distance of 10 µm under the fluid velocity of (a) 0.3 mm/s, and (b) 1 mm/s.

Figure 12

Transfer rate of NPs of diameter ranging from 10 nm to 900 to the media channel of the lung-on-a-chip device with different membrane porosities considering equal inflow velocities of (a) 0.3 mm/s and (b) 1 mm/s for air and media channels.

Figure 13

Normalized (a) average position and (b) standard deviation of transferred NPs of diameters ranging from 10 nm to 900 at the outlet of the media channel in the lung-on-a-chip device with different membrane porosities under the fluid velocity of $0.3 \mathrm{mm}/\mathrm{s}$. The solid red line corresponds with an ideal distribution in the media channel.

Figure 14

Snapshots from transient distribution of particles with a diameter of 10 nm in the lung-on-a-chip device with pore diameter and pore-to-pore distance of 10 µm and fluid velocity of 0.3 mm/s.

Figure 15

Transient relative concentration rate for NPs with different diameters. (a) $d=3$ µm, $p-p=10$ µm; $u_a=0.3$ mm/s; (b) $d=10$ µm, $p-p=5$ µm, $u_a=0.3$ mm/s; (c) $d=3$ µm, $p-p=10$ µm, $u_a=1$ mm/s; and (d) $d=10$ µm, $p-p=5$ µm, $u_a=1$ mm/s.