Optimizing the signal-to-noise ratio for biosensing with carbon nanotube transistors

Iddo Heller, Jaan Mãnnik, Serge G. Lemay, Cees Dekker*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

64 Citations (Scopus)


The signal-to-noise ratio (SNR) for real-time biosensing with liquid-gated carbon nanotube transistors is crucial for exploring the limits of their sensitivity, but has not been studied thus far. Although biosensing is often performed at high transconductance where the device displays the largest gate response, here we show that the maximum SNR is actually obtained when the device is operated in the subthreshold regime. In the ON-state, additional contributions to the noise can lead to a reduction of the SNR by up to a factor of 5. For devices with passivated contact regions, the SNR in ON-state is even further reduced than for bare devices. We show that when the conductivity of the contact regions can be increased usiπg a conventional back gate, the SNR in the ON-state can be improved. The results presented here demonstrate that biosensing experiments are best performed in the subthreshold regime for optimal SNR.

Original languageEnglish
Pages (from-to)377-382
Number of pages6
JournalNano letters
Issue number1
Publication statusPublished - Jan 2009
Externally publishedYes


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