Wearable Applanation Tonometer Pressure Sensor Module

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Solution Overview

Problem

Conventional force sensors are bulky, structurally limited, and nonlinear, making them unsuitable for small form factor applications, low-cost durable devices, and high precision applications, and they often require specialized training for installation and operation.

Innovation Solution

An interface pressure sensor system with a microelectromechanical fluid pressure sensor encapsulated in a rigid module enclosure and infill material, which redirects shear forces and concentrates sensitivity normal to the sensing surface, allowing for precise pressure measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If conventional force sensors are used, then force sensing capability is provided, but the device occupies substantial volume and area

Engineering Contradiction:

Improvesensor volumeVSAvoidforce sensitivity

Core Design Contradiction:

Volume of moving objectVSMeasurement precision

Solution Approach 1:

The patent replaces conventional mechanical force sensors with a microelectromechanical fluid pressure sensor that uses fluid pressure transmission through an encapsulation material. This substitution enables small form factor integration while maintaining high measurement precision, as the fluid pressure sensor can detect minute pressure changes with high accuracy despite its compact size.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs a thin encapsulation material layer that acts as a flexible membrane to transmit force to the pressure sensor. This thin-film approach minimizes the overall sensor volume and profile while preserving force sensing capability, allowing integration into portable and wearable devices with strict space constraints.

Inventive Principle:

Principle #30Flexible shells and thin films

2Ease of operation

If conventional force sensors are used, then force detection is enabled, but the sensors are delicate and expensive requiring specialized training

Engineering Contradiction:

Improveinstallation and operation simplicityVSAvoidsensor durability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent uses an encapsulation material that cushions and protects the delicate microelectromechanical pressure sensor from mechanical shocks and environmental damage. This protective encapsulation enhances sensor reliability and durability while maintaining ease of operation, as the robust encapsulated structure can withstand rough handling without requiring specialized installation or operation procedures.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The patent employs cost-effective microelectromechanical pressure sensors with integrated encapsulation that eliminate the need for expensive, delicate conventional sensors requiring specialized handling. The simplified design reduces both component cost and operational complexity, making the system suitable for low-cost applications while maintaining adequate reliability through the protective encapsulation structure.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Measurement precision

If conventional force sensors are used, then force sensing is provided, but the sensors have structurally-limited and nonlinear force sensitivity

Engineering Contradiction:

Improveforce sensitivity linearityVSAvoidsensor structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces an encapsulation material as an intermediary between the applied force and the pressure sensor. This intermediary layer provides a controlled, linear transmission path that enhances force sensitivity linearity while keeping the overall structure simple. The encapsulation material's uniform properties ensure consistent force distribution to the sensor, improving measurement precision without adding structural complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 accurate and precise measurement of pressure and force inputs in a compact form factor, suitable for various applications including wearable devices and medical diagnostics, without the need for specialized training.

Implementation Method 1

a microelectromechanical force or pressure sensitive structure that deforms in response

Methodology Applied

Scientific EffectDeformation: Deformation

Implementation Method 2

the encapsulation material transits that force, or at least a portion thereof, to a microelectromechanical force or pressure sensitive structure

Methodology Applied

Scientific EffectMechanical Force: Mechanical Force

Data Source

PatentUS11839450B2Pressure sensor module for wearable applanation tonometer

Publication Date: 2023.12.12 APPLE INC

AI summary

An interface pressure sensor includes a fluid pressure sensor disposed in a volume defined by a shear wall. The volume is enclosed, and the fluid pressure sensor is encapsulated by, an infill material. The infill material defines a sensing surface that, when pressed, can impart a force that is detectable by the fluid pressure sensor. The interface pressure sensor can be used for applanation tonometry.