Electrical detection of nucleic acid amplification using an on-chip quasi-reference electrode and a PVC REFET

Eric Salm, Yu Zhong, Bobby Reddy, Carlos Duarte-Guevara, Vikhram Swaminathan, Yi Shao Liu, Rashid Bashir

Research output: Contribution to journalArticle


Electrical detection of nucleic acid amplification through pH changes associated with nucleotide addition enables miniaturization, greater portability of testing apparatus, and reduced costs. However, current ion-sensitive field effect transistor methods for sensing nucleic acid amplification rely on establishing the fluid gate potential with a bulky, difficult to microfabricate reference electrode that limits the potential for massively parallel reaction detection. Here we demonstrate a novel method of utilizing a microfabricated solid-state quasi-reference electrode (QRE) paired with a pH-insensitive reference field effect transistor (REFET) for detection of real-time pH changes. The end result is a 0.18 μm, silicon-on-insulator, foundry-fabricated sensor that utilizes a platinum QRE to establish a pH-sensitive fluid gate potential and a PVC membrane REFET to enable pH detection of loop mediated isothermal amplification (LAMP). This technique is highly amendable to commercial scale-up, reduces the packaging and fabrication requirements for ISFET pH detection, and enables massively parallel droplet interrogation for applications, such as monitoring reaction progression in digital PCR.

Original languageEnglish (US)
Pages (from-to)6968-6975
Number of pages8
JournalAnalytical chemistry
Issue number14
StatePublished - Jul 15 2014


ASJC Scopus subject areas

  • Analytical Chemistry

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