Soft Haptic Actuators Matching Tissue Mechanics
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Solution Overview
Problem
Existing haptic actuators made from rigid metallic parts are unsuitable for simulating touch sensations, as they operate at high frequencies and do not efficiently transmit forces to soft human tissue, failing to effectively replicate lower frequency sensations and tactile experiences.
Innovation Solution
A soft actuator system using hydraulically amplified self-healing electrostatic (HASEL) transducers with deformable shells, fluid dielectrics, and electrodes, which apply directional forces when activated, allowing for peristaltic, wave, or pumping motions to simulate touch sensations by aligning actuators within a sleeve to match the properties of human tissue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If rigid metallic actuators are used for haptics, then high frequency operation is achieved, but effective force transmission to soft tissue and low frequency tactile simulation deteriorates
Solution Approach 1:
The patent changes the material parameters of the actuator from rigid metal to soft compliant materials, enabling the actuator to match the mechanical properties of human tissue. This parameter change allows the actuator to operate effectively at lower frequencies while maintaining good force transmission to soft tissue, resolving the contradiction between high frequency operation and effective force transmission.
Solution Approach 2:
The patent employs composite material structures combining soft compliant materials with internal mechanisms (such as pneumatic chambers, shape memory alloys, or magnetic particles) to achieve both softness for tissue compatibility and sufficient actuation force. This composite approach allows the actuator to transmit forces effectively to soft tissue while maintaining compliance, addressing the force transmission issue.
2Strength
If rigid metallic actuators are used, then structural strength is maintained, but compatibility with soft human tissue and simulation of touch sensations deteriorates
Solution Approach 1:
The patent fundamentally changes the mechanical parameter of stiffness from high (rigid metal) to low (soft compliant), making the actuator mechanically compatible with soft human tissue. This enables the actuator to safely contact and simulate touch sensations on the skin without causing discomfort or damage, while still maintaining sufficient structural integrity through alternative design approaches.
Solution Approach 2:
The patent uses composite material constructions where soft outer layers provide tissue compatibility while internal structural elements (such as reinforced frameworks, distributed actuation elements, or smart materials) maintain necessary structural strength. This composite structure resolves the contradiction between strength and tissue compatibility.
3Force
If soft actuators are used to match human tissue properties, then force transmission efficiency and tactile simulation improve, but operational frequency range may be limited
Solution Approach 1:
The patent employs dynamic actuation strategies where multiple soft actuators are activated in sequence or combination to achieve a broad frequency response. The soft actuators can be controlled to produce low frequency tactile sensations when needed, while the system can modulate activation patterns to extend the effective frequency range, resolving the contradiction between force transmission and frequency range.
Solution Approach 2:
The patent substitutes traditional high-frequency mechanical vibration mechanisms with controlled deformation and displacement of soft materials. By using pneumatic, hydraulic, or smart material actuation mechanisms instead of high-speed mechanical systems, the patent achieves effective force transmission at lower frequencies while potentially extending the operational range through controlled actuation patterns.
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 soft actuator system provides a comfortable and effective transmission of tactile information, enabling the simulation of realistic touch sensations and haptic feedback by matching the mechanical properties of human tissue, enhancing user experience in therapeutic and wellness applications.
Implementation Method 1
Application of the voltage produces directional forces on the appendage... Actuation of the plurality of actuators by application of the voltage produces a plurality of directional forces on the appendage contained within the sleeve
Data Source
AI summary
An actuator system includes a sleeve for accommodating an appendage of a user therein, actuators, and a power source. Each actuator includes a deformable shell defining a pouch including an enclosed internal cavity with a fluid dielectric contained therein, and first and second electrodes disposed over opposing sides of the pouch. The power source provides a voltage between the first and second electrodes. The sleeve includes features for distributing the actuators within the sleeve in a predetermined manner. Application of the voltage produces directional forces on the appendage. In embodiments, the first and second electrodes are disposed over the pouch such that, when the actuator is activated, the fluid dielectric is displaced in a length direction within the pouch, and the features in the sleeve may or may not align the actuators such that the length direction of the actuators are in alignment.