Photodiode Array Fabrication on Spherical Platform for 4-PI Detection
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Solution Overview
Problem
Conventional camera systems and detector arrays are limited in their field-of-view and require adhesive-based attachment methods that are bulky and prone to degradation when transforming two-dimensional structures into three-dimensional shapes, restricting their application on non-developable surfaces.
Innovation Solution
The method involves growing an epitaxial structure on a substrate, bonding it to a flexible membrane without adhesives, and using photolithographic techniques to form a sensor array, which is then cut into segments and wrapped onto target objects using origami and Van der Waals bonding, enabling 4-π detection on spherical or other non-developable surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesive-based attachment methods are used to transform two-dimensional structures into three-dimensional shapes, then the attachment is achieved, but the structure becomes bulky and prone to degradation
Solution Approach 1:
The patent removes adhesive layers from the sensor array structure, extracting the problematic intermediate layer that caused bulkiness and degradation. The sensor array is bonded directly to the curved substrate through surface treatments and bonding protocols, eliminating the adhesive-based attachment method that created structural complexity and reliability issues.
Solution Approach 2:
The patent introduces surface treatments (such as plasma treatment or chemical etching) as an intermediary mechanism to enable direct bonding between the sensor array and curved substrate. This intermediary process creates surface energy and chemical groups that facilitate strong adhesion without requiring bulky adhesive layers, resolving the contradiction between attachment reliability and structural simplicity.
2Volume of moving object
If stretching process is employed to expand two-dimensional structure into three-dimensional structure, then the expansion is achieved, but the pixel density is reduced
Solution Approach 1:
The patent employs curved and spherical substrates with predetermined geometries that match the sensor array layout. By designing the substrate to have the target curvature from the beginning, the sensor array can be bonded conformally without stretching or deformation, maintaining pixel density while achieving three-dimensional expansion. The curved substrate acts as a pre-formed template that accommodates the sensor array's geometric transformation needs.
Solution Approach 2:
The patent transitions from planar to curved/spherical geometries by utilizing the third spatial dimension. Instead of stretching the two-dimensional sensor array, the substrate itself is formed in three-dimensional curvature, allowing the array to maintain its two-dimensional integrity while achieving the desired three-dimensional form factor. This dimensionality change approach preserves manufacturing precision while enabling volumetric expansion.
3Device complexity
If conventional camera systems with planar platform are used, then the system is simple, but the field-of-view is limited to 50°×40°
Solution Approach 1:
The patent replaces planar substrates with curved and spherical substrates that have optical surfaces optimized for wide-angle or 360-degree field-of-view applications. The spherical geometry naturally provides omnidirectional light collection capability, expanding the field-of-view from limited 50°×40° to near-complete 360-degree vision while maintaining relatively simple sensor array integration through direct bonding techniques.
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 approach enhances pixel density and allows for complete 360-degree vision by eliminating the need for stretching and adhesive-based attachment, providing a flexible and durable sensor array on complex shapes like spheres and hemispheres with improved performance and reduced stress.
Implementation Method 1
bonding, without the use of an adhesive, the epitaxial structure to a flexible membrane to form a device structure
Implementation Method 2
depositing water onto the non-developable surface of the target object, placing the segments over the non-developable surface of the target object, and baking the target object, thereby bonding the segments on the non-developable surface of the target object
Data Source
AI summary
A method is presented for fabricating an array of sensors on an object having a non-developable surface. The method includes: growing an epitaxial structure on a substrate; bonding, without the use of an adhesive, the epitaxial structure to a flexible membrane to form a device structure; forming an array of sensors from the epitaxial structure of the device structure using photolithographic techniques; cutting the device structure into segments; and bonding the segments onto the target object.