AMI THUNDER High Voltage DC to DC Converter FAQs

General
Operation
Products
Performance
Materials
Cost

General                   (return to top)

            What are the most common customer applications for EPAM™?

Currently, AMI is focused on products based on the Diaphragm Actuator Configuration for applications of pumps, valves and linear actuators.

Is AMI working on other products and configurations?

AMI is continuing to work on configurations such as roll actuators, planars, sensors, generators, speakers, as well as, many other novel configurations that exploit the performance advantages of EPAM™.

What are the performance advantages of EPAM™ over other traditional actuators such as electromagnetic motors and solenoids, pneumatics, piezoelectrics?

EPAM™ is typically smaller, quieter, simpler, more versatile, more durable, and more efficient than traditional actuators.

What is the fastest way for my company to learn about EPAM™?

Companies interested in how EPAM™ works can buy the development kits listed on AMI’s web site.

Can I integrate AMI’s development kits into my product prototype?

Probably not.  AMI’s development kits are provided for new technology early adopters to independently learn about EPAM™ performance and tradeoffs such as voltage vs. displacement, frequency vs. displacement, force vs. displacement, etc.  For EPAM™ integration into customer prototypes, AMI recommends the development contract approach.

How does AMI do development contracts?

AMI has provided significant development services as outlined below.

·         Phase 0:  Engineering Feasibility Study

·         Phase 1:  Concept Prototype

o        Design and build a prototype of the product concept

o        Objective:  prove concept, form, fit and function potential

o        Evaluate and determine product design requirements

o        Elapsed time:  1 to 4 months

·         Phase 2:Develop a product version of the initial product concept

o        Further engineering analysis

o        Detailed design

o        Fabricate pre-production prototypes for testing

o        Elapsed time:  4 to 6 months

Can I purchase some raw EPAM™ material?

The performance properties of EPAM™ are dependent upon bias, configuration, and other proprietary parameters that make it most useful for customers to obtain EPAM™ as a part of an EPAM™ device or cartridge.

Does AMI make Prosthetics?

AMI is positioned as an actuator components company. Currently, AMI is not focused on developing EPAM™ for prosthetic applications.  Since powered prosthetics need linear actuators, once EPAM™ has the power output and reliability that is necessary for prosthetics, it will be possible to make a muscle for a prosthetic device.

What does EPAM™ stand for?

Electroactive Polymer Artificial Muscle

Operation                    (return to top)

Voltage and Current

What is the operating voltage of EPAM™?

While the input voltage for EPAM™ can be as low as that from a 1.5V battery, AMI provides a voltage step-up modules to drive the EPAM™ at voltages up to 5 kilovolt (kV) range, depending on the performance required in the EPAM muscle.  AMI is reducing the necessary level of voltage by several means including an automated manufacturing process and materials development.  The operating voltage will be significantly reduced in the near future while continuing to meet or exceed current performance levels.  As with most electromechanical devices, as the voltage is increased, the power output increases while the lifetime and reliability decrease.  AMI has characterized the trade-offs of power output and device lifetime, which allows AMI to select an appropriate operating voltage based on the product needs.

What input voltage is required for EPAM™?

AMI’s electronics modules accommodate 1 to 24 Volts DC as well as 100-240VAC 50-60Hz input.

What current is required for EPAM™?

The average current draw for EPAM™ actuators is very low.  Since EPAM™ is a capacitive load, current draw primarily occurs when the device is charging.  The current required is dependent upon the capacitance of the device.  Devices with higher power output require larger currents. Typical currents are 0-40 mA, which translates to low power consumption.  As an example, to move a lens 0.3mm for an auto-focus function requires less than 50 milliwatts.

Frequencies

Over what range of frequencies can EPAM™ actuators operate?

EPAM™ has a broad range of frequency operation.  Some actuators run at less than 1Hz to maximize displacement, while other actuators, such as EPAM™ speakers, run as high as 17kHz.  Frequency is one of the controllable parameters which can be used to optimize EPAM™ performance. EPAM can also be controlled in analog mode to follow an arbitrary waveform.  Many of the oscillatory devices are designed to operate at the device resonant frequencies to achieve the power peak.

Control

What is required to control EPAM™?

AMI delivers the appropriate power supply to drive each product.  The controls are dependent upon the customer requirements.  For example, a pump may have control of frequency and voltage to control the flow rate, pressure, and fluid power.  Some of the development kit configurations use the MC-02 which has three control modes: internal DC to control the voltage for proportional actuators, Internal oscillatory mode which voltage and frequency can be controlled, and external mode where analog signals can be used to control the voltage and waveform.

Products                    (return to top)

Pumps

What advantages do EPAM™ pumps have over other pump solutions?

EPAM™ pumps are silent, lighter and have more degrees of freedom, such as voltage, frequency and duty cycle, to control performance factors - like flow and pressure - than do other pump solutions. This allows EPAM™ pumps to have a high dynamic turndown ratio and a significantly broader range of controllable flow rates than conventional pumps.

What flow rates and pressures can EPAM™ pumps achieve?

These numbers are constantly improving.  By mid 2005 AMI pumps were pumping air at 4 liters per minute at 2 PSI and water at150 cubic centimeters per minute.  Liquid pumps have operated as high as 40PSI. 

Where is AMI with regard to commercially available pumps?

AMI provides a standard fluid pump (DP75) as part of the development kit offerings.  By means of a development contract, AMI can develop commercial pumps that can be delivered in volume within one year after contract initiation.

Valves

Can EPAM™ valves be on/off and proportional?

EPAM valves can be both on/off and proportional.  Like actuators, proportional valves can be controlled with varying voltage level inputs.

What advantages do EPAM™ valves have over other valve solutions?

EPAM valves are silent, lighter weight, more efficient, more repeatable, and for most applications, are lower in cost.

Generators

How is EPAM™ used as a power generator?

Electrical generation is accomplished when the distance between two layers of electrodes with an initial charge is decreased, which in turn causes the charge on the electrodes to increase.  A portion of the mechanical energy required to compress the two charged electrodes is converted into an increased electrical potential energy.  This increase in potential energy can be harvested to run EPAM™ actuators or other electrical devices.

Sensors

Can EPAM™ be used for sensor applications?

Since EPAM™ has the features of a variable capacitor and a variable resistor, force and position sensing can be accomplished by measuring the change in capacitance or resistance in the deflected EPAM™.

What is the relationship between capacitance and force for EPAM™ sensors?

This depends on the EPAM™ configuration and dielectric material.  Recent force sensing pad configurations showed 10 to 20 pF per kilogram change for one dielectric and less than 2 pF per Kilogram for another dielectric.

What resolution of force or position can you get with an EPAM™ sensor?

This depends on the design and configuration.  AMI will look at customer specifications and provide an EPAM™ design as part of our development services.

Can the same EPAM™ actuator also serve as a position sensor?

Yes, as long as the electronics are applied correctly.  One advantage of a two phase configuration, such as a double diaphragm is that one phase can be used for actuation while the other phase can close the loop as a position sensor.

Multiple Phase Actuators

What is the advantage of a two-phase actuator?

Performance.  In the case of a two-phase diaphragm and linear actuator the stroke of a two-phase actuator is double that of a corresponding one-phase actuator.   In addition, a two-phase actuator provides an inherent “midway” stroke rest position, which is desirable in some applications. In the case of bending rolls, multiple phases provide additional degrees of freedom of bending.

 Performance                    (return to top)

Displacements/Strains

What percent strain can EPAM™ achieve?

Typical operating strains of reliable EPAM™ devices in the no-load state (no-load is defined as the condition where the device does not move any force or weight through the stroke) are 5-20% over the active length of the device (Active length is defined as the length of EPAM™ film parallel to the direction of motion.  The total device length is equal to the active length plus the length of the support structure).  Maximum strains of up to 380% have been demonstrated in laboratories, but there is a tradeoff between strain and life cycles when loaded.  For applications that require high lifetimes, the actuator must be designed to operate at lower strain levels.  The strain is also dependent upon frequency.  Typically, as the frequency is increased, the strain decreases.  The strain frequency response is dependent upon material properties, configuration design, and control electronics. Development is ongoing to improve the maximum strain at which devices can be reliably operated.  Diaphragm devices typically achieve 10-30% strain of the height of the device.  Roll actuators normally get 10-20% displacement of the length of the roll for long life cycles.

Forces

What is the maximum force an EPAM™ actuator can exert?

There is no theoretical limit to the maximum force that an EPAM™ actuator can exert, but there are limits for a given volume of EPAM™ in any given component size.  EPAM™ delivers maximum force in the ‘blocked’ state (no stroke) and zero force at the maximum stroke.  There is a linear relationship between force and the number of layers.  For example, 1 layer diaphragm devices have a force of 0.5 Newtons and 20 layer devices of the diaphragm configuration have demonstrated a blocked force of 10 Newtons N.

What is the highest force AMI has attained?

AMI has reached 50 Newtons of force with a 30mm diameter linear roll.  Higher forces are possible with increased layer count or by attaching multiple actuators in parallel

What radial forces can you get from bending rolls?

Bending rolls have not been designed to deliver high radial forces.  In order to maximize bending, the structure typically has a low radial stiffness that makes it difficult to deliver a high radial force. There is less than 1 Newton of radial force on most current bending roll configurations.  Design concepts for higher radial forces are currently under development.

What are the performance tradeoffs for force?

Displacement trades off with force.  An EPAM™ actuator starts with the maximum force level (blocking force) and then decreases as it expands outward with voltage until it reaches zero force at maximum displacement.  As the number of EPAM™ layers increases, the force increases as well, though the EPAM™ device becomes physically larger.

Pressures

What pressures can be applied to an EPAM™ surface like a diaphragm?

Pressure is a function of the number of layers.  The development kit single-layer diaphragm configuration can withstand about 0.5 PSI.  The pressure that can be applied is dependent upon the size of the diaphragm.

Environmental Performance

What temperature range can EPAM™ survive?

EPAM™ can survive -50C to 100C.  Performance may change over this temperature range. 

What temperature range can EPAM™ operate?

Different dielectric materials have different operating temperature ranges.  The advantage of the silicone based dielectric is that it can operate well below freezing.  Dielectrics tend to improve their performance at high temperatures (50C+) because of the decrease in viscoelasticity.

Can EPAM™ operate in high humidity or in water?

EPAM™ has been used as the actual pump diaphragm in a liquid pump and has operated while completely submerged in water.  This is accomplished by coating of the EPAM™ surface with a sealant.

Power/Energy Density

What are some examples of EPAM™ actuator power to weight ratios.

The power to weight ratios vary by configuration.  It is important to note that the effect of power and energy density of EPAM™ can be more profound at the system level when compared to many conventional electromagnetic motor based solutions.  Many of these conventional solutions include drive trains that are not necessary with simple direct drive EPAM™ actuators.

How does AMI measure power on EPAM™ devices?

The measurement of power depends on the configuration.  For linear actuators, either a ‘Muscle Lever’ servo-motor or a linear to rotary clutch motor is used to characterize the power output.  For pumps, the power is determined by measurements of the pressure and flowrate.

Hysteresis

Do EPAM™ components exhibit hysteresis?

The significance of the level of hysteresis depends on the application.  In certain applications and configurations, EPAM™ exhibits hysteresis.  AMI characterizes effects such as hysteresis and addresses them in the course of product design to ensure that the customer’s required operating specifications are met.

Lifetime

What is AMI doing to increase the lifetime cycles of EPAM™?

AMI has a team of engineers and scientists working full time on continuous development to increase the lifetime of EPAM™. There are several factors contributing to AMI’s roadmap to billion-plus lifecycle levels, including the development of a totally automated manufacturing process which will provide more dimensional consistency, enhancements to dielectric and electrode materials, thinner individual layers of muscles for lower operating voltages, and several other proprietary developments.

How many cycles can an EPAM™ actuator last?

The lifetime of an EPAM actuator depends on several application parameters including the displacement and the applied voltage.  EPAM diaphragm cartridges have been tested to over 20-40 million cycles. Over time, AMI will continue to improve the lifetime for applications such as high frequency pumps that will run for hundreds of millions of cycles.

What are the typical failure modes of EPAM™?

EPAM™ can fail due to dielectric breakdown (an electrical short), mechanical fatigue or fracture and open circuits from leads becoming disconnected.  The AMI team of engineers and scientists are working to minimize the potential for failure of EPAM™.

Materials                    (return to top)

What Dielectric Materials Does EPAM™ use?

AMI’s EPAM™ patents are independent of dielectric materials.  AMI uses acrylic and silicone and is evaluating other dielectric materials. Materials can be utilized based on performance, environmental, reliability, and power requirements.

What material does AMI use for electrodes?

A key part of AMI’s IP is the proprietary, polymer-based electrode material.

The composition of this material is the result of many years of development and test and will remain proprietary.

Costs                    (return to top)

How much does EPAM™ Cost?

The cost of EPAM™ is highly dependent upon the volumes manufactured and the control electronics required for the application.  As an example, for a two-position valve the power supply and electronics are very simple, which can lead to a cost of a few dollars in volume production. 

How does the cost of EPAM™ solutions compare to other solutions?

There are two aspects to costs: the direct “component to component” cost and the higher level “system” cost for which the actuator is a subcomponent.  Compared to conventional actuators like electromagnetic based solutions EPAM™ is typically 25% to 75% lower cost.

The cost savings can be even higher at the system level.  As an example an EPAM™ linear roll actuator can match or exceed the performance of a motor-driven belt and ball screw device for a hydraulic valve.  The EPAM™ roll actuator solution requires less space, has significantly fewer parts, and has no moving parts, just an expanding/contracting muscle.