The ability to mechanically stimulate touch receptors over the entire body is a key feature for fully immersive and highly realistic virtual reality experience. Haptic stickers, flexible arrays of HAXELs (hydraulically amplified TAXels), that enable cutaneous haptics over nearly all parts of the body, are reported. HAXELs are zipping electrostatic actuators that combine stretchable elastomers and high permittivity flexible films to generate both high strains and high forces, from DC to 200 Hz. A fabrication process that enables scaling HAXELs from 2 to 15 mm in diameter is presented, allowing to tailor the actuators to different body parts and to wearables such as wrist‐watches. The different sizes of HAXELs generate blocked forces from 100 to 800 mN, with DC displacements from 100 to 850 µm, well above sensation thresholds. Haptics tests of Haptic Stickers, 5 × 5 arrays of 10 mm diameter devices, on palms, back of the hand, neck, arm, and back of a dozen volunteers, are done with users reporting high pattern recognition success on many body locations. The Haptic Stickers uniquely offer a thin and lightweight form‐factor, which does not limit the freedom of motion of the user, compatible with untethered scenarios.

The ability to control high-voltage actuator arrays relies, to date, on expensive microelectronic processes or on individual wiring of each actuator to a single off-chip high-voltage switch. Here we present an alternative approach that uses on-chip photoconductive switches together with a light projection system to individually address high-voltage actuators. Each actuator is connected to one or more switches that are nominally OFF unless turned ON using direct light illumination. We selected hydrogenated amorphous silicon (a-Si:H) as our photoconductive material, and we provide a complete characterization of its light to dark conductance, breakdown field, and spectral response. The resulting switches are very robust, and we provide full details of their fabrication processes. We demonstrate that the switches can be integrated into different architectures to support both AC and DC-driven actuators and provide engineering guidelines for their functional design. To demonstrate the versatility of our approach, we demonstrate the use of the photoconductive switches in two distinctly different applications-control of µm-sized gate electrodes for patterning flow fields in a microfluidic chamber and control of cm-sized electrostatic actuators for creating mechanical deformations for haptic displays.

This paper describes the feasibility of a de-icing device based on forced vibrations induced in an ice-covered rectangular aluminum plate using an amplified piezoelectric actuator. The removal of the ice layer is caused by the creation of mechanical stresses induced by relatively fast time-varying mode shapes in the very low kHz-range large enough to overcome the adhesion forces at the material/ice interface.

We present a method to control individual high-voltage actuators in an array using microfabricated photoconductive switches and a light projection system, thus overcoming the challenges of on-chip control at high voltages. Such switching capabilities go beyond actuators - our proposed approach may open the door to the simple control of other high-voltage processes, such as MEMS, pressure sensors, and RF devices.

A flexible array of high-force and high-stroke mm-scale actuators for wearable haptics will be presented. The soft actuators are capable of both of out-of-plane motion and in-plane motion, allowing the user to feel both normal forces and shear forces from the same active bump. Combining features of DEAs and HASEL devices, each actuator consists of an oil-filled cavity made of a metalized polymer perimeter and a central elastomer region. When a voltage is applied to the electrodes, the fluid is rapidly forced into the central region, forming a bump. Each actuator generates forces of up to 300 mN and displacements of up to 500 µm (60% strain), with a response time of under 10 ms. The 5x5 array is low-profile (<1 mm thick), lightweight (90 mg per actuator) and is suitable for integration in a haptic glove, sleeve or bracelet. It can also be used as a dynamic graphical display for blind or visually impaired users.

The sense of touch is underused in today’s virtual reality systems due to lack of wearable, soft, mm‐scale transducers to generate dynamic mechanical stimulus on the skin. Extremely thin actuators combining both high force and large displacement are a long‐standing challenge in soft actuators. Sub‐mm thick flexible hydraulically amplified electrostatic actuators are reported here, capable of both out‐of‐plane and in‐plane motion, providing normal and shear forces to the user’s fingertip, hand, or arm. Each actuator consists of a fluid‐filled cavity whose shell is made of a metalized polyester boundary and a central elastomer region. When a voltage is applied to the annular electrodes, the fluid is rapidly forced into the stretchable region, forming a raised bump. A 6 mm × 6 mm × 0.8 mm actuator weighs 90 mg, and generates forces of over 300 mN, out‐of‐plane displacements of 500 µm (over 60% strain), and lateral motion of 760 µm. Response time is below 5 ms, for a specific power of 100 W kg −1 . In user tests, human subjects distinguished normal and different 2‐axis shear forces with over 80% accuracy. A flexible 5 × 5 array is demonstrated, integrated in a haptic sleeve.

We present a very thin, fast and flexible fluidic valve based on a hydraulically amplified dielectric actuator. A thin cavity made by bonding flexible membranes and including central stretchable region made of silicone is filled with dielectric fluid. Under an electric field, the fluid is displaced from the edges of the cavity to the central region, inflating the center of the actuator and closing a valve. The valve dimensions are less than 10x10x1mm. The valve can block a pressure up to 1Bar in less than 10ms for a 1 mm diameter inlet using a voltage of 1.4kV. Arrays of such valves are easily fabricated with inexpensive materials.

In order to overcome the torque limitation of current piezoelectric motors we propose a new motor concept with an embedded strain wave reducer. It combines an ultrasonic motor based on a simple disk-shaped piezoelectric buzzer with a flat strain wave reducer. In this paper, we focus on the characterization of the ultrasonic piezoelectric motor for this moto-reducer.

This paper presents the preliminary work on a new concept of a piezoelectric moto-reducer for high torque application. It combines an ultrasonic motor based on a simple disk-shaped piezoelectric buzzer with a flat strain wave reducer.

Multi-degree-of-freedom angular actuators are commonly used in numerous mechatronic areas such as omnidirectional robots, robot articulations or inertially stabilized platforms. The conventional method to design these devices consists in placing multiple actuators in parallel or series using gimbals which are bulky and difficult to miniaturize. Motors using a spherical rotor are interesting for miniature multidegree-of-freedom actuators. In this paper, a new actuator is proposed. It is based on a curved piezoelectric element which has its inner contact surface adapted to the diameter of the rotor. This adaptation allows to build spherical motors with a fully constrained rotor and without a need for additional guiding system. The work presents a design methodology based on modal finite element analysis. A methodology for mode selection is proposed and a sensitivity analysis of the final geometry to uncertainties and added masses is discussed. Finally, experimental results that validate the actuator concept on a single degree-of-freedom ultrasonic motor set-up are presented.

We present a new method for electrode design in order to improve efficiency of energy conversion in piezoelectric elements used as a longitudinal-bending actuators. An analytical method of electromechanical coupling calculation based on strain analysis of a piezoelectric element is presented. This method allows for simple computation of conversion efficiency of a set of electrodes associated with a given stimulated mode. We propose an optimal electrode pattern in the case of an ultrasonic curved longitudinal-bending actuator.

Inertially stabilized platforms are widely used in order to provide a stable line-of-sight for optical components such as cameras, lasers or mirrors. They are often difficult to miniaturize because of the need for multiple degrees of freedom and high dynamic. Ultrasonic motors provide an interesting solution since they can provide high torque at low speed without the need for extra mechanical parts.

As a single working chamber for a national air kerma standard was not considered safe and robust enough, a new set of six ionization chambers was devised to establish the French 60Co air kerma standard. Although every new ionization chamber was treated as much as possible in the same way (manufacturing, measurements of volumes, wall effect calculations, current corrections), a maximum discrepancy of 0.2% was observed between the final measurement results from each chamber. The final value of the air kerma rate in reference conditions was determined as the mean value of the measurement results from all six chambers. Among the different factors whose determination is necessary to calculate the air kerma rate, some are considered independent of or common to all the graphite-walled ionization chambers (example: mean energy expended by an electron to produce an ion pair in dry air), while others vary for each chamber (example: air cavity ionic collection volume). Considering that the uncertainties of the individual ionization chamber measurement results seem slightly underestimated, the uncertainty on the mean of the products of the six chamber-dependent factors was taken equal to the standard deviation of the sample composed of the products of the six chamber-dependent factors (0.078%). Compared with the previous standard, the air kerma rate of the 60Co photon beam would then increase by 0.09% and the air kerma rate uncertainty would drop from 0.38% to 0.31%.