Abstract We developed graphene FET (G-FET) arrays combined with a portable microfluidic measurement system for SARS-CoV-2 detection. Multiple G-FETs modified with SARS-CoV-2 spike antibodies and those not modified were integrated onto the same chip. By calculating the difference in the FET-responses, we aimed to minimize noise including virus physisorption and baseline drifts. The microfluidic system was used to change ionic strengths of buffers without manual pipetting. The virus was incubated in a high ionic strength solution, followed by electrical measurements in a low ionic strength solution, leading to effective binding and electrical detection. Upon introducing the virus at a concentration of 10⁸ virus ml⁻¹, a response of 7.9 mV was obtained. To confirm whether the response was attributed to the virus, we employed a scanning electron microscope (SEM). SEM observation indicates that the virus was much adsorbed on the antibody-modified surface compared to the non-modified surface, which agrees with the G-FET response.