Dielectric Elastomer Eyelid Actuation for Low-Heat Symmetric Blinking
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Solution Overview
Problem
Existing solutions for restoring blinking function in patients with facial paralysis, such as goggles, surgical procedures, and nerve grafting, significantly impact quality of life and have limitations in heat generation, bulkiness, or operational inefficiencies, while current artificial muscle technologies face low actuation frequencies and compliance issues.
Innovation Solution
An implantable electromechanical device using a dielectric elastomer actuator with a rod and spring mechanism, which is flexible and thin enough to be hidden under the skin, providing unidirectional eyelid actuation and synchronized with the healthy side for symmetric blinking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a conventional coil-based electric motor is used to actuate the eyelid, then the motor can provide sufficient force, but the motor generates heat that is difficult to evacuate and requires a large volume that is hardly available near the eyelid
Solution Approach 1:
The patent replaces the conventional coil-based electric motor with a dielectric elastomer actuator (DEA) that uses electrostatic fields to generate mechanical force. This substitution eliminates the need for coils and commutators that generate heat, while providing sufficient actuation force through the electrostatic attraction between electrodes deforming the elastomer membrane.
Solution Approach 2:
The patent changes the operating parameters from electromagnetic (coil-based motor) to electrostatic (dielectric elastomer). This parameter change fundamentally alters the heat generation characteristics, as electrostatic actuators convert electrical energy to mechanical work with minimal resistive heating compared to coil-based systems.
2Force
If a conventional coil-based electric motor is used to actuate the eyelid, then the motor can provide sufficient force, but the motor requires a volume that is hardly available anywhere near the eyelid
Solution Approach 1:
The patent replaces the bulky coil-based motor with a thin-film dielectric elastomer actuator that can be fabricated as a flexible membrane only micrometers thick. This electrostatic actuator provides the necessary force while occupying minimal volume that can be comfortably implanted near the eyelid.
Solution Approach 2:
The patent employs a dielectric elastomer membrane as the active element of the actuator. This thin-film structure, typically only a few micrometers to millimeters thick, provides the necessary mechanical force while maintaining a compact, flexible form factor suitable for implantation near the eyelid where space is constrained.
3Shape
If pneumatic artificial muscles are used to restore blinking function, then the actuators can produce motion of contraction and expansion, but they are cumbersome and require pumps and compressors
Solution Approach 1:
The patent replaces pneumatic artificial muscles that require external pumps and compressors with a dielectric elastomer actuator that uses electrical voltage to generate mechanical deformation. This substitution eliminates the need for complex pneumatic infrastructure while achieving similar contraction and expansion motions.
Solution Approach 2:
The patent achieves pneumatic-like expansion and contraction motions through electrostatic actuation of the dielectric elastomer membrane. When voltage is applied, the membrane expands in-plane and contracts in thickness, mimicking the bellows-like motion of pneumatic muscles without requiring actual pneumatic systems.
4Shape
If shape memory alloys are used to restore blinking function, then the actuators can produce motion of contraction and expansion, but they present lower compliance and slow response times
Solution Approach 1:
The patent replaces shape memory alloys that exhibit slow response times due to thermal diffusion limitations with a dielectric elastomer actuator that responds almost instantaneously to electrical voltage changes. The electrostatic actuation mechanism enables rapid deformation without the thermal lag inherent in SMA materials.
Solution Approach 2:
The patent changes the actuation mechanism from thermal (SMA requiring heat input) to electrostatic (DEA using voltage input). This parameter change fundamentally improves response time, as electrostatic fields establish and collapse almost instantaneously compared to the thermal diffusion processes required for shape memory alloy actuation.
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 device effectively restores blinking function with minimal heat generation and bulk, requiring no nerve grafts, offering real-time symmetric movement and reducing the need for continuous energy use, thus improving ocular health and quality of life.
Implementation Method 1
Dielectric Elastomer Actuators (DEAs) is a recent type of EAP that converts electrical energy into mechanical work
Implementation Method 2
The DEA may consist of a silicone layer sandwiched between two conductive electrodes: when a voltage is applied on the electrodes, a compressive Maxwell stress is generated, inducing a thickness reduction and thus an expansion in the other dimensions
Data Source
Figure 1~2B
Figure 3A~4
Figure 5~6
AI summary
Electromechanical implantable device for actuating a patient's eyelid (11), comprising an actuator (2) for activating the opening or closing of the eyelid. The actuator is a dielectric elastomer actuator. The device may comprise a rod (3). The actuator is intended to be implanted under the skin of the patient's forehead, and linked to the eyelid via said rod.