Session: Analytical Division Poster:

Point-of-care (POC) platforms for detecting emerging pathogens have been a significant barrier against meeting the threat of COVID-19. One of the critical issues has been the absence of modularity that allows researchers to rapidly tune their existing POC platforms to emerging threats. Further, significant challenges like sensitivity and selectivity of the POC device while meeting the “ASSURED” requirements have always been the bottleneck. Recently, we demonstrated a novel modular, non-planar, interdigitated, flow-through, porous electrode called ESSENCE. ESSENCE utilizes fluidic shear and convective forces to disrupt the parasitic double layer and other diffusive processes in a microfluidic channel. Further, ESSENCE’s porous structure facilitates the measurement of Electrochemical Impedance Spectroscopy (EIS) signal from low frequencies (~ 10 Hz) to high frequencies (~ 10kHz), making ESSENCE rapid with a high signal to noise ratio. A broad range of nano-ordered materials with coupled capture molecules against different chemical and biological target analytes of interest can be used in ESSENCE. This enhances the sensitivity and selectivity of ESSENCE while allowing multiplexing and a modular approach. However, ESSENCE is hindered by the packing losses during the measuring process, resulting in a loss in reliability and quantification with long device priming times. We have successfully mitigated this issue by introducing a poly(amic acid) (PAA) porous manifold that contains the packing material to form the non-planar interdigitated electrode. The PAA manifold is fabricated using the standard phase-inverted method. SEM, BET, FTIR, and Raman are used to characterize the manifold's uniformity and porosity. We show that ESSENCE version 2 has ten times higher flow enhancement, high reliability, and easy quantification than ESSENCE version 1 with this manifold. This also dramatically decreased the priming time due to its higher flow resistance in the channel. ESSENCE version 2 has femtomolar sensitivity and high selectivity against multiple different targets, including cancer biomarkers like HER2, P53, and Ki67, DNA and RNA’s in physiological fluids like blood plasma, serum, and urine. This shows ESSENCE’s promise as a POC device for the rapid detection of emerging pathogens.

Lixin Feng

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