Ion Sensor Film Width and Electrode Separation
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Solution Overview
Problem
The existing ion sensor with an aperture type structure faces challenges in securing a sufficient contact area between the ion sensitive film and the medium, limiting its sensitivity due to constraints on the size of the opening and pixel pitch.
Innovation Solution
The ion sensor incorporates a charge storage portion, multiple electrodes, and an ion sensitive film configuration where the ion sensitive film is wider than the separation between electrodes, allowing for improved contact area and sensitivity through controlled potential changes transmitted via the electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If an aperture type structure is used with electrodes and ion sensitive film at the bottom of opening, then the pixel size and pitch requirements are met, but the contact area between ion sensitive film and medium is insufficient
Solution Approach 1:
The invention transitions from a two-dimensional aperture structure to a three-dimensional stacked structure. The ion sensitive film is extended in the thickness direction of the substrate, forming a protruding structure that increases the contact area with the medium. This dimensional change allows the ion sensitive film to extend beyond the opening plane, effectively increasing the sensing area without increasing the pixel pitch or compromising the aperture structure.
Solution Approach 2:
The ion sensitive film is nested within the opening structure, with the film extending from the bottom of the opening upward along the thickness direction. This nested configuration allows the ion sensitive film to utilize the vertical space within the pixel structure, maximizing the contact area with the medium while maintaining compact pixel dimensions and adhering to pitch requirements.
2Measurement precision
If the opening size is increased to improve contact area, then the sensitivity improves, but the pixel pitch and integration density are compromised
Solution Approach 1:
Instead of increasing the opening size in the planar direction (which would increase pixel pitch), the invention extends the ion sensitive film in the thickness direction. This vertical extension increases the contact area and sensitivity without expanding the pixel footprint, thereby maintaining small pixel pitch and high integration density.
Solution Approach 2:
The ion sensitive film is concentrated in the region of the opening, with enhanced local contact area through vertical extension. This localized quality enhancement ensures that the sensitivity improvement is focused where the medium contacts the film, while the overall pixel dimensions remain compact for high-density integration.
3Area of stationary object
If the ion sensitive film width is increased beyond electrode separation, then the contact area improves, but the charge transfer efficiency may be compromised
Solution Approach 1:
The ion sensitive film is extended in the thickness direction rather than only in the lateral direction. This vertical extension increases the contact area with the medium while maintaining the film's alignment with the underlying electrodes. The film width in the planar direction can remain matched to the electrode separation, preserving charge transfer efficiency through the vertical electric field between electrodes.
Solution Approach 2:
The ion sensitive film exhibits different functional zones: the lateral width is optimized for charge transfer alignment with electrodes, while the vertical extension provides enhanced contact area with the medium. This local quality differentiation allows simultaneous optimization of both charge transfer efficiency and sensing area.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances the sensitivity of the ion sensor by ensuring a larger contact area and efficient charge transfer, overcoming the limitations of the aperture type structure.
Implementation Method 1
an ion sensitive film configured to change a potential in accordance with a change in ion concentration of a medium in contact with the ion sensitive film
Implementation Method 2
a charge storage portion formed in a region of the substrate along a first surface, and configured to accumulate charges to be injected into a potential well formed in a portion of the substrate
Implementation Method 3
The first electrode is disposed on the first surface, and configured to control an amount of charge injection from the charge storage portion to the potential well. The second electrode is disposed on the first surface, and is configured to perform control for transferring charges from the potential well to the outside.
Data Source
AI summary
The ion sensor includes a substrate and a plurality of detection units. Each detection unit includes an ID portion, an ICG electrode, a TG electrode, an SG electrode, an electrode pad, and an ion sensitive film. The SG electrode is disposed between the ICG electrode and the TG electrode on the main surface of the substrate. The electrode pad is electrically connected to the SG electrode and disposed on the opposite side of the SG electrode from the substrate. The ion sensitive film is provided on the surface of the electrode pad, and changes a potential according to change in ion concentration of the aqueous solution in contact with the ion sensitive film. A width of the ion sensitive film in a facing direction in which the ICG electrode and the TG electrode face each other is greater than a separation width between the ICG electrode and the TG electrode.