Development and Application of a Polydimethylsiloxane-Based Passive Air Sampler to Assess Personal Exposure to SARS-CoV-2

Abstract

Exhaled respiratory droplets and aerosols can carry infectious viruses and are an important mode of transmission for COVID-19. Recent studies have been successful in detecting airborne SARS-CoV-2 RNA in indoor settings using active sampling methods. The cost, size, and maintenance of these samplers, however, limit their long-term monitoring ability in high-risk transmission areas. As an alternative, passive samplers can be small, lightweight, and inexpensive and do not require electrical power or maintenance for continual operation. Integration of passive samplers into wearable designs can be used to better understand personal exposure to the respiratory virus. This study evaluated the use of a polydimethylsiloxane (PDMS)-based passive sampler to assess personal exposure to aerosol and droplet SARS-CoV-2. The rate of uptake of virus-laden aerosol on PDMS was determined in lab-based rotating drum experiments to estimate time-weighted averaged airborne viral concentrations from passive sampler viral loading. The passive sampler was then embedded in a wearable clip design and distributed to community members across Connecticut to surveil personal SARS-CoV-2 exposure. The virus was detected on clips worn by five of the 62 participants (8%) with personal exposure ranging from 4 to 112 copies of SARS-CoV-2 RNA/m 3 , predominantly in indoor restaurant settings. Our findings demonstrate that PDMS-based passive samplers may serve as a useful exposure assessment tool for airborne viral exposure in real-world high-risk settings and provide avenues for early detection of potential cases and guidance on site-specific infection control protocols that preempt community transmission.

Comparison of Airborne Bacterial Populations Determined by Passive and Active Air Sampling at puy de Dôme, France

“…Passive samplers do not require any external power or an air mover and rely on gravity, diffusion, and/or electrostatic forces to collect airborne particles, including bioaerosols. Passive sampling devices based on these collection principles include spore traps (Durham, 1946;Serrano-Silva and Calderón-Ezquerro, 2018), dust collectors (Cox et al, 2017), agar settling plates (Andon, 2006), polydimethylsiloxane pads (Angel et al, 2022), and specially-arranged polarized ferroelectric polymer films (Therkorn et al, 2017a). In particular, electrostatic collection combined with gravitational particle deposition can allow for greater collection efficiency of bioaerosols compared to gravitational settling alone (Therkorn et al, 2017b).…”

Silicone Foam for Passive Sampling and Nontarget Analysis of Air

“…Evidence indoors suggested that foam accumulated a higher molecular weight fraction of polar substances, likely associated with particles, and visible inspection of PDMS foam deployed outdoors revealed particles after only 1 week (Figure S12). As it has been done for PDMS sheets, , the uptake rate of PDMS foam could be quantitatively calibrated to define the useful linear-uptake period for gaseous- and particulate-phase analytes. In future real-world applications, incorporating diffusive barriers into the deployment casings around PDMS could reduce variability between people or locations, but such barriers must be designed to minimally interfere with collection of the airborne fine particulate fraction.…”

Advancements in Airborne Viral Nucleic Acid Detection with Wearable Devices

“…Existing strategies for collecting viruses and other pathogens from the air and concentrating them for downstream characterization can be divided into two broad classes, those relying on active air sampling and those relying on passive (diffusive) air sampling (Figure 2). [30,52,53] Both collection mechanisms have advantages and disadvantages to integrating them into wearable sensors for the detection of airborne pathogens. Recent studies have primarily relied on active air samplers to study the spread of airborne viruses such as SARS-CoV-2 and Influenza A, both in hospital and commercial settings.…”

“…Unlike ac-tive air samplers, passive samplers do not require forced airflow and instead let aerosol particles settle and adsorb onto a collection substrate like polydimethylsiloxane (PDMS) or filter-paper under ambient air conditions. [52,53,60] The lack of a pumping unit tends to make passive air samplers simpler to use and operate than active samplers and they tend to be smaller. For example, setups as simple as electrostatic cloth attached to a folder and a small PDMS pad in a wearable clip have been used as passive air samplers.…”

“…For example, setups as simple as electrostatic cloth attached to a folder and a small PDMS pad in a wearable clip have been used as passive air samplers. [52,59] Small size and simplicity are obvious advantages of using passive air samplers instead of active samplers in integrated wearable sensors for detection of airborne viral RNA. However, since passive samplers utilize much lower airflow rates, they suffer from long collection times.…”