Mobile COVID-19 Sample Collection Booth: Design Concept

APPLICATION BRIEF
Mobile COVID-19 Sample Collection Booth
In today’s highly contagious environment, it is important to reduce the spread of the

COVID-19 virus. One way to reduce the spread of infection at the community level is through
early detection, which requires that large numbers of people be tested in a short time.
Presently, testing is limited to people who are showing symptoms of COVID-19. To test
more widely, hospitals need to build facilities for mass testing. Traditional laboratory-based
sample collection methods are not suitable for testing large numbers of people during the
community transmission phase. A separate sample collection method needs to be
implemented for the general public following BSL-3 standards.
This document proposes the design of a mobile COVID-19 sample collection booth that
can be assembled quickly and moved easily to facilitate sample collection from urban and
remote areas. The safety of the sample collection staff and persons visiting the booth to
be
Tested has utmost priority according to BSL-3 standards. South Korea has already adopted
Such a testing booth, and they found it to be effective in flattening out the curve.
Products Used:
/ Design Concept
The main objective of the COVID-19 sample collection booth is to avoid
direct contact between the sample collecting staff and the person
providing the sample. Further, the next person visiting the booth
should not become infected by the nasal or oral plumes of the
previous person. The overall sample collection time — including
changing plastic gloves and disinfecting the booth — should not be
more than five to seven minutes per person, so that a
Large number of samples can be
collected in a day. The booths are
built on the negative pressure room
(NPR) concept, which involves
maintaining a negative pressure
In the room so that air inside the
room does not leak out through the
gaps. Air from inside the booth is
Discharged outside in a Figure 1. COVID-19 sample collection
controlled booth used in South Korea
Manner after filtering.
Mobile COVID-19 Sample Collection Booth // 1

Figure 1 shows the mobile COVID-19 sample collection booth used in South Korea [4]. The booth consists
of a negative pressure cabin for the person giving the sample and works on the principle of a bio safe,
isolation glove box design. The sample is collected in the following manner:
1. Sample collecting staff stays outside of the cabin wearing PPE kit.
2. Person enters the disinfected cabin, removes mask and talks by speaker phone with the
sample collecting staff to provide the required information.
3. Sample collecting staff collects the swab sample using glove-box-style hand gloves fitted to the cabin.
4. Person leaves the cabin after putting the mask back on.
5. A staff member of the sample collection team changes the plastic gloves, disinfects the room
and puts the sample in a box.
6. The cabin is then ready for the next person.
/ Proposed Design
In the proposed design, negative pressure is maintained in the
booth to prevent leakage of any contaminants outside. Smoke
detection can be done at the key openings to ensure that air is
moving inwards.
Ventilated air is discharged outside the room and filtered through a
portable HEPA filtration unit to discard cleaned exhaust to the outside
environment. The air flow rate is set to around 24 air changes per
hour so that it takes approximately 2.5 minutes to ventilate most of
the room air. The air flow rate can be controlled using a flow control
valve before the HEPA filter/blower unit. The medical staff interacts
with the patient through an isolation glove box to avoid physical
contact or direct air contact. This flow ventilation system is designed
Figure 2. Proposed design of COVID-19
and validated with computational fluid dynamics (CFD) modeling. The sample collection booth
flow rate is selected so that the expelled gases from the patient’s
breathing, coughing or sneezing are directly ventilated outward
without much circulation in the room.
Figure 2 shows the proposed design. It consists of multiple sample collection cabins with dimensions of 2.5
ft. x 2.5 ft. x 7 ft., each with a door. A square 45-degree downward louver is fitted 6 in. above the ground on
the door of the cabin. A circular exhaust duct is fitted in the center at the top of the cabin. The transparent
wall of the cabin has two circular holes for glove-box-style hand gloves. The exhaust duct is connected to
an exhaust system consisting of a HEPA filter and exhaust blower. The sizes of the inlet vent and circular
exhaust are selected such that the flow area at the inlet and exhaust are similar. Table 1 shows the overall
dimensions and operating parameters for the cabin.
Table 1. Dimensions of COVID-19 Sample Collection Booth Cabin
Parameter Value
Cabin dimensions 2.5 ft. x 2.5 ft. x 7 ft.
Inlet vent size 10 in. x 5 in.
Inlet vent location 6 in. above the ground
Exhaust vent diameter 8 in.
Air Flow rate 24 air changes per hour (ACH)
Exhaust velocity ~1fps

The following is a list of materials needed to build a sample collection booth:
1. Acrylic sheets
2. Aluminum frame
3. 45-degree downward louver
4. 125 cubic feet per minute (CFM) HEPA filter/blower unit [7-8]
5. Power backup unit (small generator if needed)
6. 8 in. ID flexible hose
7. Flow control valve (if the HEPA unit does not have provision for flow control)
8. Fumigation system to disinfect the unit
9. PPE kits BSL-2 equipped
10.Rubber gloves
/ Design Validation Using Computational Fluid Dynamics

The proposed design was validated, as shown in Figure 3. The figure
Contaminated area of the cabin that needs proper
shows the volume rendering of air velocity. The path lines show the
disinfection
paths of the nasal or oral plumes of the person providing the
sample. Results show that the nasal and oral plumes are swept out
of the cabin easily toward the exhaust without a large recirculation
within the cabin.
Thus, the design is suitable and ensures minimum contamination
of the cabin in case the person providing the sample is COVID-19
positive. Results also highlight the area that needs to be
disinfected properly before the next person enters the cabin.
/ Summary Figure 3. Validation of proposed

design for sample collection booth
This document explains the design of a COVID-19 sample collection booth. The proposed design can be
used as a stationary unit or mounted on a small truck as a mobile unit. The booth can be built quickly to
test large numbers of patients at a rate of roughly seven minutes per patient. BSL level 2 specifications
can be achieved with the correct choice of materials listed in World Health Organization guidelines and
as proposed above. To meet BSL 2 specifications, the final exhaust gas discharge region should be
located far enough away that it does not come close to the booth or the inlet vents.
/ References
1. Laboratory Testing Strategy Recommendations for COVID-19, Interim Guidance, March 2020
2. Laboratory Biosafety Manual, Third Edition, 2004
3. WHO interim guidelines for Laboratory for COVID-19, Feb 2020
4. South Korean Hospital’s ‘Phone Booth’ Coronavirus Tests
5. How South Korea Flattened the Curve, The New York Times, March, 2020
6. ANSYS, Inc
7. RPS Ventilation Unit
8. Ventilation Design Guidelines for booth, tents and room
/ Appendix I / Appendix II
Assembly of the Sample Collection Booth Biological Safety Levels (BSL)
Figure 4. Assembly of sample collection booth
/ Appendix III
Steps for Operating Sample Collection Booth
Step 1. Disinfected booth is ready for sample collection Step 2. Person giving the sample enters the booth, staff-1
collects sample, leaves the virus transport tube on the corner
shelf in the booth
Step 3: Person who gave sample leaves the booth Step4: While the next person in the queue waits outside, staff-2
(i) keeps the viral transport media (VTM) in a leak-proof Zip-Lock
pouch and puts it in icebox
(ii) removes the outer plastic gloves from the nitrile gloves
(iii) disinfects the inside of the booth all over
(iv) puts fresh plastic gloves on the nitrile gloves
Step 5: Disinfected booth is ready for next sample collection
/ Appendix IV

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APPLICATION BRIEF

Mobile COVID-19 Sample Collection Booth

In today’s highly contagious environment, it is important to reduce the spread of the

Mobile COVID-19 Sample Collection Booth // 1

6. The cabin is then ready for the next person.

Table 1. Dimensions of COVID-19 Sample Collection Booth Cabin

Inlet vent size 10 in. x 5 in.

Inlet vent location 6 in. above the ground

Exhaust vent diameter 8 in.

Air Flow rate 24 air changes per hour (ACH)

Exhaust velocity ~1fps

/ Design Validation Using Computational Fluid Dynamics

/ Summary Figure 3. Validation of proposed

Figure 4. Assembly of sample collection booth

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