CMUT Ultrasonic Touch Detection for Underwater Reliability
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Solution Overview
Problem
Capacitive touch sensors fail to operate reliably when submerged in water, and mechanical buttons are prone to water damage and mechanical failure, necessitating a reliable touch detection solution for underwater environments.
Innovation Solution
An ultrasonic touch sensor using capacitive micromachined ultrasonic transducers (CMUTs) that can differentiate between touch and no-touch events, even when submerged in water, by analyzing ultrasonic reflected waves and employing a mode detection circuit to adjust operation thresholds based on environmental conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitive touch sensors are used, then touch detection capability is provided, but reliability deteriorates when submerged in water
Solution Approach 1:
The patent replaces capacitive touch sensing with ultrasonic wave-based touch detection. The system uses ultrasonic transducers to emit sound waves that reflect off the touch surface, converting electrical energy to acoustic energy and back to electrical signals for processing. This substitution eliminates the water interference problem inherent in capacitive sensors while maintaining touch detection capability in underwater environments
Solution Approach 2:
The patent introduces ultrasonic waves as an intermediary medium between the sensor and the touch surface. Instead of directly detecting capacitance changes at the touch interface (which are blocked by water), the system uses reflected ultrasonic waves to indirectly detect touch events, allowing reliable operation underwater
2Reliability
If mechanical buttons are used, then touch input is achieved, but reliability deteriorates due to water damage and mechanical failure
Solution Approach 1:
The patent eliminates mechanical components entirely by using ultrasonic transducers for touch detection. The system employs capacitive micromachined ultrasonic transducers (CMUTs) that can operate in underwater environments without mechanical moving parts, thereby preventing water damage and mechanical failure while maintaining touch input functionality
Solution Approach 2:
The ultrasonic transducers are designed to be inherently resistant to water damage, requiring no additional protection mechanisms. The system self-adapts to underwater conditions through automated threshold adjustment based on environmental detection, eliminating the need for mechanical seals or protective housings
3Adaptability or versatility
If ultrasonic sensors operate in water environment, then touch detection is enabled, but measurement precision deteriorates due to different acoustic properties
Solution Approach 1:
The patent implements dynamic threshold adjustment where the measurement circuit automatically modifies detection thresholds based on real-time environmental conditions. The mode detection circuit identifies whether the sensor is operating in air or water mode and adjusts corresponding thresholds accordingly, enabling precise touch detection across different environments without manual intervention
Solution Approach 2:
The system changes operational parameters including detection thresholds and signal processing characteristics based on the operating environment. By detecting environmental conditions and adjusting parameters dynamically, the system maintains measurement precision whether operating in air or underwater, adapting to acoustic property variations
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 reliable touch detection in water environments, distinguishing between direct and indirect touches, and maintaining functionality without water infiltration or mechanical failure.
Implementation Method 1
capacitive ultrasonic transmitter arranged within the ultrasound chamber, wherein the capacitive ultrasonic transmitter is configured to receive the first excitation signal and transmit the first ultrasonic transmit wave
Implementation Method 2
capacitive ultrasonic receiver arranged within the ultrasound chamber, wherein the capacitive ultrasonic receiver is configured to receive a first ultrasonic reflected wave and generate a first measurement signal representative of the first ultrasonic reflected wave
Implementation Method 3
a first ultrasonic reflected wave produced by a reflection of the first ultrasonic transmit wave at the touch interface
Data Source
AI summary
An ultrasonic touch sensor includes a touch structure including a touch surface configured to receive a touch, a signal generator configured to generate an excitation, a capacitive ultrasonic transmitter configured to transmit an ultrasonic transmit wave toward the touch structure based on the excitation signal while the touch surface is submerged under the water, a capacitive ultrasonic receiver configured to receive an ultrasonic reflected wave produced by a reflection of the ultrasonic transmit wave at the touch structure while the touch surface is submerged under the water and generate a measurement signal representative of the ultrasonic reflected wave, and a measurement circuit configured to perform a comparison based on the measurement signal and a threshold, and determine whether a no-touch event or a touch event has occurred at the touch surface while the touch surface is submerged under the water based on whether the measurement signal satisfies the threshold.