Silicon multi-nanochannel FETs to improve device uniformity/stability and femtomolar detection of insulin in serum

Here we demonstrate the use of multiple Si nanochannel (NC) or nanograting (NG) instead of the conventional single nanochannel or nanowire design in biosensors. The NG devices can significantly reduce device-to-device variation, and improve device performance, e.g. higher current, higher ON/OFF ratio, smaller subthreshold slope, lower threshold voltage Vt in buffer solution. NG devices also result in higher sensor stability in buffer and diluted human serum. We believe such improvements are due to reduced discrete dopant fluctuation in the Si nanowires and biochemical noise in the solution because of the multiple-channel design. The improved devices allow us to sense pH linearly with 3-aminopropyltriethoxysilane coated devices, and to selectively detect insulin with limit of detection down to 10 fM in both buffer solution and diluted human serum without pre-purification.

► Multi-nanowire FETs reduces random doping fluctuation and outperform single-nanowire devices.
► We found multi-nanowire FET biosensor provides excellent repeatability and uniformity.
► We show that SiN passivation of biosensor is effective to avoid damage from electrolyte solution.
► We report repeatable pH sensing with excellent linearity using multi-nanowire biosensors.
► We demonstrate insulin detection from human serum with detect limit down to 10 fM.