Phononic Crystal Bolometer Beams for Infrared Sensor Cooling
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Solution Overview
Problem
Infrared sensors face a trade-off between detection sensitivity and response speed due to the heat-insulation performance of phononic crystal structures, which reduces thermal conductance but slows temperature changes, and the use of Peltier devices increases thermal conductance, reducing sensitivity while attempting to improve response speed.
Innovation Solution
An infrared sensor design featuring a bolometer with phononic crystal beams and a Peltier device with phononic crystal beams, where the Peltier device is interposed between the bolometer and a recess in the base substrate, maintaining low thermal conductance while effectively cooling the bolometer using semiconductor materials with improved Peltier effect through phononic crystal structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phononic crystal structures are used to improve heat-insulation performance, then detection sensitivity is improved, but response speed deteriorates
Solution Approach 1:
The beam is divided into multiple segments: a first beam portion with phononic crystal structure for thermal insulation, and a second beam portion without phononic crystal structure for thermal conduction. This segmentation allows the beam to simultaneously achieve both heat insulation and rapid heat dissipation functions in different regions.
Solution Approach 2:
Different portions of the beam are assigned different thermal properties: the first beam portion has low thermal conductivity (phononic crystal structure) while the second beam portion has high thermal conductivity (no phononic crystal structure). This local differentiation enables the beam to provide thermal insulation where needed while maintaining rapid heat dissipation capability.
2Speed
If Peltier devices are used to improve response speed, then response speed is improved, but detection sensitivity deteriorates
Solution Approach 1:
The Peltier device is positioned only in the second beam portion (without phononic crystal structure), creating a local cooling zone. This localized approach allows rapid temperature recovery without significantly affecting the overall thermal insulation performance of the bolometer, thus maintaining detection sensitivity while improving response speed.
Solution Approach 2:
The second beam portion acts as an intermediary thermal pathway, conducting heat from the bolometer to the Peltier device for active cooling. This intermediary structure enables rapid heat dissipation while the first beam portion maintains the thermal insulation needed for sensitive detection.
3Measurement precision
If thermal conductance is reduced to improve sensitivity, then detection sensitivity is improved, but temperature change speed deteriorates
Solution Approach 1:
The thermal pathway is segmented into two portions with opposite thermal conductance characteristics. The first portion provides high thermal resistance for sensitivity, while the second portion provides low thermal resistance for rapid temperature change, resolving the contradiction between sensitivity and response speed.
Solution Approach 2:
The system operates in periodic cycles: during the detection phase, the phononic crystal structure maintains thermal insulation for sensitive measurement; during the recovery phase, the second beam portion enables rapid heat dissipation. This periodic operation allows the system to alternate between high sensitivity and fast response modes.
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
The design achieves both high detection sensitivity and rapid response speed by reducing thermal conductance and enhancing the Peltier effect, allowing for efficient cooling of the infrared ray receiver.
Implementation Method 1
the phononic crystal structure is capable of reducing the thermal conductivity of the base material itself structuring the thin film
Implementation Method 2
Formation of the phononic band gap (PBG) by virtue of the phononic crystal structure can largely reduce the thermal conductivity of the material
Implementation Method 3
a Peltier device having the shape of a beam connected to the base substrate so as to be in contact with the infrared ray receiver. By virtue of the Peltier device locally absorbing heat from the infrared ray receiver, the temperature of the infrared ray receiver which has been raised by incident infrared rays lowers
Implementation Method 4
a bolometer infrared ray receiver comprising a resistance variable layer in which resistance varies upon absorption of an infrared ray
Data Source
AI summary
An infrared sensor comprises a base substrate including a recess, a bolometer infrared ray receiver, and a Peltier device. The bolometer infrared ray receiver comprises a resistance variable layer, a bolometer first beam, and a bolometer second beam. The Peltier device comprises a Peltier first beam formed of a p-type semiconductor material and a Peltier second beam formed of an n-type semiconductor material. The Peltier device is in contact with a back surface of the bolometer infrared ray receiver. One end of each of the bolometer first beam, the bolometer second beam, the Peltier first beam, and the Peltier second beam is connected to the base substrate. The bolometer infrared ray receiver and the Peltier device are suspended above the base substrate. Each of the bolometer first beam, the bolometer second beam, the Peltier first beam, and the Peltier second beam has a phononic crystal structure including a plurality of through holes arranged regularly.