MEMS Bolometer Anchor Resistive Switching

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Solution Overview

Problem

MEMS bolometer devices face challenges in incorporating switching mechanisms to control current flow, leading to continuous power consumption and limited functionality in applications like infrared cameras and thermal imaging sensors, where individual bolometers cannot be effectively turned ON/OFF.

Innovation Solution

Integration of a resistive switching mechanism using a metal oxide layer stack within the MEMS device, allowing for selective application of DC voltages to transition between high and low resistive states, enabling current control and allowing bolometers to be turned ON/OFF.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a switching mechanism is incorporated into the MEMS bolometer device, then current flow can be controlled and power consumption can be reduced, but the device complexity increases

Engineering Contradiction:
Improvepower consumptionVSAvoiddevice complexity
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent combines the switching mechanism with the anchor structure by forming a resistive switch within the anchor structure itself. The bottom insulator layer and top conductive layer are integrated into the anchor structure fabrication process, merging the structural support function with the electrical switching function. This allows current control without adding separate switching components, thereby reducing power consumption while minimizing the increase in device complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The anchor structure serves dual purposes: it provides mechanical support to suspend the bolometer and simultaneously functions as a resistive switch for controlling current flow. The bottom insulator layer and top conductive layer within the anchor structure enable it to switch between high and low resistive states, allowing the same structure to perform both mechanical and electrical control functions.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If individual bolometers can be selectively switched ON/OFF, then functionality in infrared cameras and thermal imaging sensors is improved, but the device complexity increases

Engineering Contradiction:
ImprovefunctionalityVSAvoiddevice complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The switching capability is merged into the anchor structure of each bolometer, allowing individual bolometers to be selectively activated or deactivated. This integration enables independent control of each pixel in an infrared camera or thermal imaging sensor array without requiring separate switching circuitry for each element, thereby improving functionality while managing device complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

Each bolometer's anchor structure contains its own resistive switch, enabling the bolometer to control its own current flow independently. This self-service capability allows individual pixels to be selectively addressed and controlled without complex external switching networks, improving the adaptability of infrared imaging devices while keeping the control mechanism relatively simple.

Inventive Principle:
Principle #25Self-service

3Reliability

If continuous current flows through the transducer element, then the bolometer functions continuously, but power is consumed at all times including standby mode

Engineering Contradiction:
Improvecontinuous operationVSAvoidstandby power consumption
Core Design Contradiction:
ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The resistive switch in the anchor structure enables periodic or selective activation of the bolometer by transitioning between high and low resistive states. Current flows through the transducer element only when the switch is in the low resistive state, allowing the bolometer to function continuously when needed while consuming minimal power during standby or inactive periods, thus reducing standby power consumption while maintaining operational reliability.

Inventive Principle:
Principle #19Periodic action

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

Enables zero stand-by power consumption and selective addressing of individual bolometers, improving thermal imaging capabilities by optimizing infrared radiation detection and reducing the need for separate circuit components.

Implementation Method 1

The base portion of the at least one anchor structure is configured as a resistive switch such that, when the first DC voltage is applied to the patterned conductive layer, the base portion transitions from a high resistive state to a low resistive state, and, when the second DC voltage is applied to the patterned conductive layer, the base portion transitions from a high resistive state to a low resistive state.

Methodology Applied
Scientific EffectResistive switching: Electrical Resistance

Implementation Method 2

Infrared radiation incident upon the bolometer will be absorbed by the absorber element of the bolometer and the heat generated by the absorbed radiation will be transferred to the transducer element.

Methodology Applied
Scientific EffectAbsorption of infrared radiation: Absorption (EM radiation)

Implementation Method 3

A transducer having an electrical resistance that varies with temperature is provided in thermal contact with absorber. As the transducer element heats in response to the absorbed radiation, the electrical resistance of the transducer element will change in a predetermined manner.

Methodology Applied
Scientific EffectTemperature dependent resistance: Electrical Resistance

Data Source

PatentEP3230702B1Resistive switching for MEMS devices
Publication Date: 2020.03.04 ROBERT BOSCH GMBH
  • EP3230702B1 patent drawingFigure 1(a)~1(c)
  • EP3230702B1 patent drawingFigure 2
  • EP3230702B1 patent drawingFigure 3~4

AI summary

A MEMS device includes a bolometer attached to a silicon wafer by a base portion of at least one anchor structure. The base portion comprises a layer stack having a metal- insulator-metal (MIM) configuration such that the base portion acts as a resistive switch such that, when the first DC voltage is applied to the patterned conductive layer, the base portion transitions from a high resistive state to a low resistive state, and, when the second DC voltage is applied to the patterned conductive layer, the base portion transitions from a high resistive state to a low resistive state.