Effect of Plasma Treatment on the Sensor Properties of a Light‐Addressable Potentiometric Sensor (LAPS)

Abstract

A light‐addressable potentiometric sensor (LAPS) is a field‐effect‐based (bio‐) chemical sensor, in which a desired sensing area on the sensor surface can be defined by illumination. Light addressability can be used to visualize the concentration and spatial distribution of the target molecules, e.g., H+ ions. This unique feature has great potential for the label‐free imaging of the metabolic activity of living organisms. The cultivation of those organisms needs specially tailored surface properties of the sensor. O2 plasma treatment is an attractive and promising tool for rapid surface engineering. However, the potential impacts of the technique are carefully investigated for the sensors that suffer from plasma‐induced damage. Herein, a LAPS with a Ta2O5 pH‐sensitive surface is successfully patterned by plasma treatment, and its effects are investigated by contact angle and scanning LAPS measurements. The plasma duration of 30 s (30 W) is found to be the threshold value, where excessive wettability begins. Furthermore, this treatment approach causes moderate plasma‐induced damage, which can be reduced by thermal annealing (10 min at 300 °C). These findings provide a useful guideline to support future studies, where the LAPS surface is desired to be more hydrophilic by O2 plasma treatment.

Efficient Illumination for a Light-Addressable Potentiometric Sensor

“…As an extreme case, if the photon energy is so high as to cause ionization/deionization in the insulator or at the insulator-semiconductor interface, as in the case of a vacuum ultraviolet light, it can alter the properties of the field-effect structure, including the flatband condition [13]. Even in the case of visible light, most of the light power is eventually converted into heat inside the semiconductor layer, which raises the temperature of the sensor plate.…”

P3.11 - “All-in-one” cell-based biosensor for on-site monitoring of cell response

“…PT was performed as described in ref. [9]. Afterwards, the wettability changes were observed by water contact angle measurements.…”

“…The lightaddressable potentiometric sensor (LAPS) can be used as a biosensor, for which different regions (measurement sites) on the sensor surface can be addressed by light illumination [5][6][7][8]. This feature represents a remarkable advantage in achieving spatial resolution in biosensing applications [9,10]. For example, using a LAPS chip that has a pH-sensitive transducer layer, a desired sensing point on the sensor surface can be addressed to measure the extracellular acidification (EA) of the cells above that region [11].…”