LAPS and SPIM Imaging Using ITO-Coated Glass as the Substrate Material

Area of Science:

• Sensor Technology
• Materials Science
• Analytical Chemistry

Background:

• Light-addressable potentiometric sensors (LAPS) and scanning photo-induced impedance microscopy (SPIM) are crucial for spatiotemporal imaging.
• These techniques rely on photocurrent measurements to map ion concentrations, electrical potentials, and impedance.
• Traditional ultrathin silicon substrates are expensive and limit the cost-effectiveness of these imaging modalities.

Purpose of the Study:

• To investigate indium tin oxide (ITO)-coated glass as a novel, cost-effective substrate for LAPS and SPIM.
• To evaluate the photocurrent generation and imaging capabilities of ITO-coated glass.
• To determine the feasibility of using ITO as a robust alternative to silicon substrates.

Main Methods:

• Illumination of ITO-coated glass with a 405 nm diode laser at anodic potentials to induce photocurrent.
• Scanning focused laser beam across the ITO surface to demonstrate light addressability.
• Characterization of AC photocurrent and pH response of ITO.
• Imaging a model system (PMMA dot on ITO) to assess lateral resolution.

Main Results:

• ITO-coated glass successfully produced photocurrents under laser illumination at anodic potentials.
• ITO exhibited good AC photocurrent and pH response without requiring surface modification or insulators.
• Light addressability of ITO was confirmed through localized photocurrent generation.
• A lateral resolution of approximately 2.3 μm was achieved using ITO as the substrate.

Conclusions:

• ITO-coated glass is a viable, low-cost, and robust substrate for LAPS and SPIM applications.
• The material demonstrates excellent photocurrent generation and imaging capabilities, comparable to traditional substrates.
• This development offers a more accessible platform for advanced electrochemical imaging.