Study of parasitic resistance effects in nanowire and nanoribbon biosensors

• Published in: Nanoscale research letters Vol. 10; no. 1; p. 79
• Main Authors: Zeimpekis, Ioannis, Sun, Kai, Hu, Chunxiao, Thomas, Owain, de Planque, Maurits RR, Chong, Harold MH, Morgan, Hywel, Ashburn, Peter
• Format: Journal Article
• Language: English
• Published: Boston Springer US 21.02.2015; Springer Nature B.V; BioMed Central Ltd
• Subjects: Chemistry and Materials Science; Materials Science; Molecular Medicine; Nano Express; Nanochemistry; Nanoscale Science and Technology; Nanotechnology; Nanotechnology and Microengineering; Nanowire; Parasitic resistance; Nanoribbon; Differential biosensor; Biosensor; pH sensor
• ISSN: 1931-7573; 1556-276X; 1556-276X
• DOI: 10.1186/s11671-015-0794-6

In this work, we investigate sensor design approaches for eliminating the effects of parasitic resistance in nanowire and nanoribbon biosensors. Measurements of pH with polysilicon nanoribbon biosensors are used to demonstrate a reduction in sensitivity as the sensor length is reduced. The sensitivity (normalised conductance change) is reduced from 11% to 5.5% for a pH change from 9 to 3 as the sensing window length is reduced from 51 to 11 μm. These results are interpreted using a simple empirical model, which is also used to demonstrate how the sensitivity degradation can be alleviated by a suitable choice of sensor window length. Furthermore, a differential sensor design is proposed that eliminates the detrimental effects of parasitic resistance. Measurements on the differential sensor give a sensitivity of 15%, which is in good agreement with the predicted maximum sensitivity obtained from modeling.