Novel photoexcitation method for light-addressable potentiometric sensor with higher spatial resolution

Abstract

A novel photoexcitation method for the light-addressable potentiometric sensor (LAPS) is proposed to achieve a higher spatial resolution of chemical images. The proposed method employs a combined light source that consists of a modulated light probe, which generates the alternating photocurrent signal, and a ring of constant illumination surrounding it. The constant illumination generates a sheath of carriers with increased concentration which suppresses the spread of photocarriers by enhanced recombination. A device simulation was carried out to verify the effect of constant illumination on the spatial resolution, which demonstrated that a higher spatial resolution can be obtained.

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

“…Theoretical analysis and LAPS device simulation have been developed continuously alongside experimental techniques to improve the lateral resolution 11,[17][18][19][20][21][22][23][24][25][26][27][28][29][30] . The spatial resolution in LAPS is limited by the diffusion of minority charge carriers out of the illuminated region, which depends on the size of illuminated area and the average effective diffusion length of minority charge carriers.…”

Device Simulation of the Light-addressable Potentiometric Sensor with a Novel Photoexcitation Method for a Higher Spatial Resolution

“…This leads to a drop of the photocurrent at the center, and thus the steepness of the decay of the photocurrent as a function of lateral distance becomes smaller. It was also demonstrated that a higher intensity and a longer wavelength of constant light resulted in a higher spatial resolution [7].…”

Recent Developments of High-Resolution Chemical Imaging Systems Based on Light-Addressable Potentiometric Sensors (LAPSs)

“…To improve spatial resolution, an auxiliary illumination of constant light can be added around the modulated light [117,118,119,120]. As shown in Figure 5a, a ring-shaped constant illumination increases the photocarriers concentration, and the enhanced recombination will block the lateral diffusion of photocarriers induced by the modulated light.…”