Highly sensitive,scalable,and rapid SARS-CoV-2 biosensor based on In_(2)O_(3)nanoribbon transistors and phosphatase

Developing convenient and accurate SARS-CoV-2 antigen test and serology test is crucial in curbing the global COVID-19 pandemic.In this work,we report an improved indium oxide(In2O3)nanoribbon field-effect transistor(FET)biosensor platform detecting both SARS-CoV-2 antigen and antibody.Our FET biosensors,which were fabricated using a scalable and cost-efficient lithography-free process utilizing shadow masks,consist of an In_(2)O_(3)channel and a newly developed stable enzyme reporter.During the biosensing process,the phosphatase enzymatic reaction generated pH change of the solution,which was then detected and converted to electrical signal by our In_(2)O_(3)FETs.The biosensors applied phosphatase as enzyme reporter,which has a much better stability than the widely used urease in FET based biosensors.As proof-of-principle studies,we demonstrate the detection of SARS-CoV-2 spike protein in both phosphate-buffered saline(PBS)buffer and universal transport medium(UTM)(limit of detection[LoD]:100 fg/mL).Following the SARS-CoV-2 antigen tests,we developed and characterized additional sensors aimed at SARS-CoV-2 IgG antibodies,which is important to trace past infection and vaccination.Our spike protein IgG antibody tests exhibit excellent detection limits in both PBS and human whole blood((LoD):1 pg/mL).Our biosensors display similar detection performance in different mediums,demonstrating that our biosensor approach is not limited by Debye screening from salts and can selectively detect biomarkers in physiological fluids.The newly selected enzyme for our platform performs much better performance and longer shelf life which will lead our biosensor platform to be capable for real clinical diagnosis usage.

Gold-vapor-assisted chemical vapor deposition of aligned monolayer WSe2 with large domain size and fast growth rate

Orientation-controlled growth of two-dimensional(2D)transition metal dichalcogenides(TMDCs)may enable many new electronic and optical applications.However,previous studies reporting aligned growth of WSe2 usually yielded very small domain sizes.Herein,we introduced gold vapor into the chemical vapor deposition(CVD)process as a catalyst to assist the growth of WSe2 and successfully achieved highly aligned monolayer WSe2 triangular flakes grown on c-plane sapphire with large domain sizes(130μm)and fast growth rate(4.3μm·s^−1).When the aligned WSe2 domains merged together,a continuous monolayer WSe2 was formed with good uniformity.After transferring to Si/SiO2 substrates,field effect transistors were fabricated on the continuous monolayer WSe2,and an average mobility of 12 cm^2·V^−1·s−1 was achieved,demonstrating the good quality of the material.This report paves the way to study the effect of catalytic metal vapor in the CVD process of TMDCs and contributes a novel approach to realize the growth of aligned TMDC flakes.

Air-stable n-type transistors based on assembled aligned carbon nanotube arrays and their application in complementary metal-oxide-semiconductor electronics

Carbon nanotubes(CNTs)are ideal candidates for beyond-silicon nano-electronics because of their high mobility and low-cost processing.Recently,assembled massively aligned CNTs have emerged as an important platform for semiconductor electronics.However,realizing sophisticated complementary nano-electronics has been challenging due to the p-type nature of carbon nanotubes in air.Fabrication of n-type behavior field effect transistors(FETs)based on assembled aligned CNT arrays is needed for advanced CNT electronics.Here in this paper,we report a scalable process to make n-type behavior FETs based on assembled aligned CNT arrays.Air-stable and high-performance n-type behavior CNT FETs are achieved with high yield by combining the atomic layer deposition dielectric and metal contact engineering.We also systematically studied the contribution of metal contacts and atomic layer deposition passivation in determining the transistor polarity.Based on these experimental results,we report the successful demonstration of complementary metal-oxide-semiconductor inverters with good performance,which paves the way for realizing the promising future of carbon nanotube nano-electronics.