Rapid, robust virus-detection techniques with ultrahigh sensitivity and selectivity are required for the outbreak of the pandemic coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). Here, we report that the femtomolar concentrations of single-stranded ribonucleic acid (ssRNA) of SARS-CoV-2 trigger ordering transitions in liquid crystal (LC) films decorated with cationic surfactant and complementary 15-mer single-stranded deoxyribonucleic acid (ssDNA) probe. More importantly, the sensitivity of the LC to the SARS ssRNA, with a 3-bp mismatch compared to the SARS-CoV-2 ssRNA, is measured to decrease by seven orders of magnitude, suggesting that the LC ordering transitions depend strongly on the targeted oligonucleotide sequence. Finally, we design a LC-based diagnostic kit and a smartphone-based application (app) to enable automatic detection of SARS-CoV-2 ssRNA, which could be used for reliable self-test of SARS-CoV-2 at home without the need for complex equipment or procedures.

对于由严重急性呼吸系统综合症冠状病毒2（SARS-CoV-2）引起的大流行冠状病毒病2019（COVID-19）的爆发，需要具有超高灵敏度和选择性的快速，强大的病毒检测技术。在这里，我们报道SARS-CoV-2的飞摩尔浓度的单链核糖核酸（ssRNA）在装饰有阳离子表面活性剂和互补的15-mer单链脱氧核糖核酸（ssDNA）的液晶（LC）膜中触发有序转变探测。更重要的是，与SARS-CoV-2 ssRNA相比，LC对SARS ssRNA的灵敏度为3 bp失配，降低了7个数量级，这表明LC的排序转换很大程度上取决于目标寡核苷酸序列。最后，