Solenoids vs. HASEL
Updated: Jan 31, 2022
HASEL actuators are an excellent alternative to solenoids for applications that require linear motion in a compact and simple package. HASEL actuators have several advantages over solenoid actuators, but a key benefit of HASEL actuators is that they consume very little power and do not generate heat while activated. In contrast, solenoids require a continuous supply of power to hold a position and they generate a significant amount of heat. The following video illustrates this difference with thermal imaging of HASEL and solenoid actuators operating side-by-side.
Below is a more detailed comparison of these two technologies that provides additional insight into the potential benefits of HASEL actuators over solenoids.
Solenoids and HASEL actuators make use of two different but related fundamental branches of physics - electromagnetics and electrostatics, respectively.
Solenoids rely on electromagnetic forces which are generated by applying current through a coil of wire. Typically a metal rod or plunger is located in the middle of the coil so that the electromagnetic force causes the plunger to move in a linear motion.
HASEL actuators rely on electrostatic forces which are generated by applying a constant voltage to the electrodes that are separated by layers of liquid and polymer dielectrics. The resulting electric field acts on the dielectric layers which displaces the liquid dielectric and causes the overall actuator structure to change shape.
Power consumption and heat generated
Solenoids require constant current and power to hold a position. This limits solenoid application to those with low-duty cycles or that do not require a position to be held actively for long periods of time. Often solenoids require methods to dissipate heat which may involve passive or active cooling.
On the other hand, HASEL actuators require little to no power while maintaining a position. Therefore, HASEL actuators are a better alternative for applications that require longer duty cycles, the ability to hold positions, require low power consumption, and/or are intolerant of temperature changes.
Materials and Parts
There are several benefits related to the materials and components used for HASEL actuators. While the coil, plunger, and case of solenoid must be made from metal, HASEL actuators can be made without any metal parts which can be beneficial for some operating environments and may reduce system weight.
Additionally, HASEL actuators do not have any moving parts; the liquid-filled structure of a HASEL actuator acts as a single composite structure. Solenoids produce audible clicking sounds as parts slide and contact each other, but HASEL actuators are virtually silent during operation.
HASEL actuators are not limited by a single form factor. They can be designed in a variety of different shapes and sizes to meet the needs of a specific application. Once again, the simple structure of HASEL actuators makes it easier to integrate them into different systems and structures. The flexible materials even make it possible to integrate HASEL actuators into clothing or accessories for wearable actuator applications.
Push vs. Pull
Similar to solenoid actuators, HASEL actuators generally provide push or pull forces only. Artimus Robotics offers contracting actuators, which pull, and expanding actuators, which push. Of course, the operation of these actuators can be modified for different types of motion.
Considerations for Using HASEL Actuators
When it comes to powering HASEL actuators, it is important to keep in mind that they require high voltage. In order to apply a large enough electric field, the voltage applied to HASEL actuators is typically 6 - 8 kV. However, the current is low (< 1 mA) and as a result, the actuators are safe, despite the high voltage. Proper insulation of the actuators and electronics is needed to prevent arcing to equipment or people. Experts at Artimus Robotics are able to guide on best practices for insulation and isolation of HASEL actuators for safe and successful operation. Artimus Robotics also offers specialized HV power supplies for the control and operation of HASEL actuators.
Another consideration when choosing a HASEL actuator over a solenoid is the force and stroke required. Just like solenoids, the force from a HASEL actuator decreases with increasing stroke. Additionally, for a given force requirement, the footprint of a suitable HASEL actuator may be larger than that of a solenoid. You can refer to the products page for standard product performance information, but HASEL actuators can be easily customized to suit a specific application so contact Artimus Robotics at firstname.lastname@example.org to discuss customization options.
Potential Applications for HASEL Actuators over Solenoids
Finally, below are a few applications where HASEL actuators provide a superior solution over solenoids:
Short stroke linear motion applications that require holding position(s) for extended periods of time.
Latches, diverters, and proportional valves. Especially those that have 2 or more active states that must be maintained with long duty cycles.
Applications requiring linear motion without any metal or magnetic parts (e.g. MRI machine).
Applications such as haptics where compliance and slim form factors are important.
About Artimus Robotics
Artimus Robotics designs and manufactures soft electric actuators. The technology was inspired by nature (muscles) and spun out of the University of Colorado. HASEL (Hydraulically Amplified Self-healing ELectrostatic) actuator technology operates when electrostatic forces are applied to a flexible polymer pouch and dielectric liquid to drive shape change in a soft structure. These principles can be applied to achieve a contracting motion, expanding motion, or other complex deformations. For more information, please visit Artimus Robotics or contact email@example.com.