Detection of Target ssDNA Using a Microfabricated Hall Magnetometer with Correlated Optical Readout
Figure 2
(a) Optical microscopy characterization (wide-field fluorescence and DIC overlay) of three-strand DNA assembly is shown by the presence of green fluorescence indicating the presence of probe DNA. (b) SEM was used to evaluate the location and to quantify the number of nanobeads contributing to the Hall response for (iii), where the grey box designates the location of the underlying Hall junction. (c) Hall responses for three active junctions (i, ii, iii) and a single control junction (iiic) are plotted as Hall voltage offset versus time; the presence of nanobeads over the active Hall junctions results in a drop in Hall voltage when a dc magnetic field is applied. (d) The theoretical device signal stemming from a single 344 nm SPM bead is shown to the right as a function of position over the Hall junction further illustrating the local sensitivity of Hall magnetometry. Scale bars = 2 μm in (a) and (b).
