Development of a mobile laboratory system in hydrogen fuel cell buses and evaluation of the performance for COVID-19 RT-PCR testing

Abstract

We designed and developed two new types of hydrogen fuel cell (HFC) buses (motorcoach and minibus) with a mobile laboratory system. Feasibility studies have been performed for mobile laboratory testing, particularly for the laboratory performance of COVID-19 RT-PCR (PCR). We evaluated the driving range capability, PCR sample size capacity, turnaround time (TAT), and analytical performance for the detection of SARS-CoV-2. Saliva samples were used for the current study, and the analytical performance was compared with that of the reference PCR. The estimated driving range and sample size capacity of the HFC and HFC minibus were 432 km and 2847 samples, respectively, for the HFC motorcoach and 313 km and 1949 samples for the HFC minibus. For the TAT, the median time between sample submission and completion of PCR was 86 min for the motorcoach and 76 min for the minibus, and the median time between sample submission and electronic reporting of the result to each visitor was 182 min for the motorcoach and 194 min for the minibus. A secondary analysis of 1574 HFC mobile laboratory testing samples was conducted, and all negative samples were found to be negative by reference PCR. Furthermore, all samples were confirmed to be positive by reference PCR or other molecular examinations.

Figure 1

(a) Shows general information about two hydrogen fuel cell buses (motorcoach type and minibus type). (b) Shows the power supply function and the power receiving function. The logo of the University of Tsukuba and the "Fuel cell Bus" logo on the car has been carefully covered up by the authors.

Figure 2

(a) Shows the flow of the laboratory system in buses, (b) shows a picture of the interior of the motorcoach-type hydrogen fuel cell bus, and (c) shows the flow of the electronic reservation and reporting systems.

Figure 3

Hydrogen fuel consumption for driving and laboratory testing (COVID-19 RT-PCR). Points a–g in the figure indicate laboratory test sites. a: Tsuchiura Public Health Center, b: Ryugasaki Public Health Center, c: Chikusei Public Health Center, d: Itako Public Health Center, e: Ibaraki Prefectural Office, f: Hitachinaka Public Health Center, g: Hitachi Public Health Center. The maps were created by the authors using Adobe Illustrator ver.28.0. (https://www.adobe.com/). The estimated maximum power of the driving distance and the laboratory testing throughput of COVID-19 RT-PCR of the hydrogen fuel cell bus were calculated according to the hydrogen storage of each bus (motorcoach, 24 kg; minibus, 9.7 kg) and average hydrogen consumption. The difference in driving distance between each bus is due to the driving route of each bus from the University of Tsukuba to the destination. The driving distance was calculated by Google Maps for the motorcoach and by the onboard distance calculation system for the minibus. The data on the average temperature of each site on the examination date were cited from the data on the website of the Japan Meteorological Agency; https://www.jma.go.jp/jma/indexe.html. The temperature inside the buses during the examination was not recorded. RT-PCR, reverse transcription-polymerase chain reaction.