Electrochemical assays have typically suffered from poor sensitivity compared to optical technology. In addition, they sometimes have a large background signal which makes detection of analyte difficult. However, the ability to detect the analyte in turbid or complex signal is the holy grail that is usually very difficult with optical methods. Many laboratories have struggled with the issue. For a good but dated, review on Electrochemical DNA sensors lookup: Nature Biotech. Vol 21 1192 (2003).
Shana Kelley, a researcher at University of Toronto has found a unique method to detect compounds electrochemically. They developed a Nuetralizer Displacement Assay(NDA) using aptamers. Traditionally, a analyte molecule binds to the sensor and generates a signal. However, in Kelly’s method the sensor is pre-bound to a neutralizer entity that binds to the sensor. The displacement of the neutralizer by the detected analyte generates a bigger signal and is not prone to random noise. In many ways, this is a unique thought process, wherein, removal of the neutralizer requires a detected-analyte that has higher binding capacity than the neutralizer. This may affect the detection limit, but on the other hand this removes the background noise very effectively and is a boon for electrochemical based detection. Expect other companies to utilize the same thought process. (Nat Chem Vol 4 642-648. 2012)