Light-Activated Electrochemistry for the Two-Dimensional Interrogation of Electroactive Regions on a Monolithic Surface with Dramatically Improved Spatial Resolution

Abstract

The concept of light-activated electrochemistry (LAE) was recently presented where faradaic electrochemistry could be spatially resolved on a monolithic silicon electrode by illuminating the specific region with light. A major implication from the previous study using illumination from the nonsolution side, or backside, is that the spatial resolution is limited by the finite thickness of silicon wafer. To overcome this restriction, and enable the further application of LAE, in combination with optical imaging for example, herein the spatial resolution of LAE using topside illumination (illumination from the solution side) is explored. The applied potential and irradiated light intensity are found to have significant effects on the spatial resolution. A spatial resolution of ∼30 μm was achieved with optimal parameters, which is a 20 times improvement compared with the previously reported backside illumination design, demonstrating the potential application of the strategy including microarray patterning of silicon or for single cell analysis.

Light-addressable Electrodes for Dynamic and Flexible Addressing of Biological Systems and Electrochemical Reactions

“…When scanning across the deposited lines, the FWHM of the related current fits to the structures down to 30 µm (Figure 8c). Furthermore, the authors stated that a top-side illumination is beneficial for the spatial resolution and additionally studied the effects of different light intensities and applied potentials [96]. Finally, as silicon as bulk material is opaque, amorphous silicon (a-Si) was deposited on ITO glass and the ferrocene was attached to 1,8-nonadiyne by the previously described CuAAc click reaction.…”

Monitoring the heterogeneity in single cell responses to drugs using electrochemical impedance and electrochemical noise

“…Shining light on a given location transiently activates that region of the electrode such that it becomes electrochemically active whilst the rest of the surface remains electrochemically inactive. 23,24 This means that any area can be electrochemically addressed on a monolithic surface with only one connecting lead.…”

Modulated light-activated electrochemistry at silicon functionalized with metal-organic frameworks towards addressable DNA chips

“…However, the intrinsic drawback of LAPS is that no DC currents cross the interface, which inhibits the electrochemical reactivity of the interface and therefore the scope of the technology is limited to potentiometric measurements (Poghossian and Schöning 2014;Wu et al 2019). Light-addressable electrochemistry or light-activated electrochemistry (LAE) (Choudhury et al 2017;Seo et al 2018;Vogel et al 2019;Yang et al 2016;Yang et al 2018), which is based on an electrolyte-semiconductor (ES) structure, overcomes this limitation. Light with constant intensity is used to generate electron-hole pairs in a semiconductor biased towards depletion resulting in a DC photocurrent output.…”

“…However, the electrochemistry of bare silicon has proven to be very challenging as it is not stable in aqueous media. In DC photocurrent measurement systems, silicon substrates are usually protected with self-assembled organic monolayers (Choudhury et al 2017;Yang et al 2016;Yang et al 2018).…”