A MICROFLUIDIC BIOSENSOR FOR RAPID DETECTION OF COVID-19 Sura A. Muhsin 1 , Ying He 2,3,4 , Muthana Al-Amidie 1 , Karen Sergovia 2,3,4 , Amjed Abdullah 1 , Yang Wang 2,3,4 , Omar Alkorjia 1 , Robert A. Hulsey 5 , Gary L. Hunter 5 , Zeynep Erdal 5 , Ryan J. Pletka 5 ,George S. Hyleme 5 , Xiu-Feng Wan 1,2,3,4 , and Mahmoud Almasri 1 1 Department of Electrical Engineering and Computer Science, College of Engineering; 2 Center for Influenza and Emerging Infectious Diseases; 3 Department of Molecular Microbiology and Immunology, School of Medicine; 4 Bond Life Sciences Center, University of Missouri, Columbia, Missouri, USA. 5 Black and Veatch, Overland Park, Kansas. ABSTRACT We have designed, fabricated, and tested a MEMS- based impedance biosensor for accurate and rapid detection of severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) using of clinical samples. The device consists of focusing region that concentrate low quantities of the virus present in the samples to a detectable threshold, trap region hat maximize the captured virus, and detection region to detect the virus with high selectivity and sensitivity, using an array of interdigitated electrodes (IDE) coated with a specific antibody. Changes in the impedance value due to the binding of the SARS-COV-2 antigen to the antibody will indicate positive or negative result. The device was able to detect inactivated SARS-COV-2 antigen present in phosphate buffer saline (PBS) with a concentration as low as 50 TCID50/ml in 30 minutes. In addition, the biosensor was able to detect SARS-COV-2 in clinical samples (swabs) with a sensitivity of 84 TCID50/ml, also in 30 minutes. KEYWORDS Microfluidic channel, MEMS, biosensor, SARS-COV-2, dielectrophoresis, microfabrication. INTRODUCTION COVID-19 pandemic expects to cause multiple waves and remains to become an endemic disease in the future [1]. As November 20 of 2022, it has caused > 634 million laboratories confirmed infections worldwide, of which > 6.59 million were fatal. The total estimated deaths caused by COVID-19 infection in the United States alone were > 1.07 million [2,3,4,5]. The majority of the currently FDA-approved tests to detect COVID viruses are nucleic acid- based on methods and monoclonal antibody based rapid antigen test (RAT). The nucleic acid based methods such as RT-PCR has high sensitivity and specificity but take up to six hours to obtain the results [4]. The recent Abbott Diagnostics’s nucleic acid-sequence based method requires as short as 15 minutes; however, the data for sensitivity and specificity is still not publicly available [5]. Nevertheless, these methods can result in potential false negative results due to rapid mutations in viruses, especially RNA viruses such as COVID-19 [6]. RAT, particularly the strip paper, is a rapid immunoassay with the results acquired within approximately 15 minutes and has been widely for self- test. However, RAT can reliably detect viral loads in the clinical samples with 3,000 TCID50/ml [7] thus cannot detect viruses during early stage of diseases Multiple diagnosis platforms for diagnosis of COVID-19 were released in the past several months [8]. Of those methods, the antibody-based testing is proved to be rapid and reliable to identify infection. A countless number of groups have investigated various diagnostic techniques for point-of-care (POC) as well as self-detection kits. However, the sensitivity of these kits depends on period of time between infection and testing to produce and detectable response of IgM [9]. We rapidly developed a diagnostic method to detect the SARS-COV-2 virus in clinical samples. Given the limits of present testing, it is evident that a more sensitive, real-time, field deployable detection approach is urgently needed to make testing reliable and feasible, which might have a significant impact on virus surveillance. MATERIALS AND METHODS Biosensor Design The device consists of fluidic microchannel, which include a region for focusing the SARS-COV-2 virus into the centerline of this region and directing them toward the detection region to obtain highly concentrated samples, a trapping region surrounding the detection electrodes, and detection region (Figure 1). The focusing region consists of two set of electrode pairs, each set uses a ramp down vertical electrode pair made of electroplated gold along with tilted thin film finger pairs with a ramp down channel that generates positive dielectrophoresis (p-DEP) forces to focus and concentrate the bacteria into the center of the microchannel, and direct them toward the sensing microchannel. This ensures detection of low concentrations of the virus. The virus detection region consists of two set interdigitated electrode (IDE) arrays surrounded by the trapping electrode pairs. The first set is used for virus detection, while the second set is used for negative control. It was not coated with antibody. The trapping electrodes is used to trap the virus on top of the detection electrode. It is made of electroplated gold with a thickness of 15 m. The biosensor was sealed using PDMS and wire-bonded to a printed circuit board. Device Fabrication Methodology The biosensor was fabricated on a glass substrate using surface micromachining processing steps. Figure 2 shows a side view along with optical images of the fabricated focusing, trapping and detection electrode and the packaged device. The glass substrate was first cleaned using piranha solution for a 3 minutes. The Pirhana consists of a mixture of hydrogen peroxide (H2O2) and sulfuric acid (H2SO4) with a ratio of 1 : 3. The substrate was then washed using DI water and blown dry with 978-1-6654-9308-6/23/$31.00 ©2023 IEEE 433 IEEE MEMS 2023, Munich, GERMANY 15 - 19 January 2023 2023 IEEE 36th International Conference on Micro Electro Mechanical Systems (MEMS) | 978-1-6654-9308-6/23/$31.00 ©2023 IEEE | DOI: 10.1109/MEMS49605.2023.10052321 Authorized licensed use limited to: University of Missouri Libraries. Downloaded on September 02,2023 at 18:12:22 UTC from IEEE Xplore. Restrictions apply.