Fabrication and characterization of SMA film actuator array with bias spring for high-power MEMS tactile display

Xu, Jiale; Kimura, Yusuke; Tsuji, Katsunori; Abe, Katsuhito; Shimizu, Tomomi; Hasegawa, Hiroyasu; Matsukawa, Takashi

doi:10.1016/j.mee.2020.111307

Cited by 11 publications

(8 citation statements)

References 6 publications

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“…Rapid development in the field of virtual reality (VR) and associated technologies has recently sprouted considerable research interest in tactile displays [1]. Tactile sensation is one of the principal sensory functions in the human body, specifically, the information received corresponding to varying vibrations and pressure against the skin [2]. A tactile display is an intelligent device that can mimic several physical modalities depending on the application, such as texture, temperature, shape, position and motion [3].…”

Section: Introductionmentioning

confidence: 99%

“…The distance between each taxel is determined by the two-point discrimination threshold (TPDT), in human fingertips, which is 1.5 -3 mm, thus for most tactile displays this is the minimum taxel separation [14]. NiTi is favoured as an actuator for a tactile display due to its relatively large displacement and high actuating force in space-constrained applications; this is in comparison to other actuators of a similar size [2]. The SME phenomena in NiTi are influenced by the fabrication process, a combination of annealing at a specific temperature, cold work and post-heat treatment, comprehensively determining its characteristics.…”

Section: Introductionmentioning

confidence: 99%

“…The thermal effects on adjacent taxel actuators when NiTi is used have not been researched much. A few researchers have glimpsed the evidence of thermal interference between adjacent NiTi actuators but there has not been an investigation into the effects as the researchers were focusing on the control element [2] [19] [20]. Thus, the focus of this paper shall be solemnly on investigating the effects of the thermal radiation between adjacent NiTi taxel actuators in a Tactile Display.…”

Section: Introductionmentioning

confidence: 99%

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An Investigation of the Effects of Thermal Interference between Adjacent Nitinol Spring Actuators in a Tactile Display

Sekerere¹,

Ndeda²,

Karanja³

2023

WJET

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Over the years, there has been increased research interest in the application of Nitinol as an actuator, due to its shape memory behaviour, simplicity, high power-to-weight ratio, compactness, and extreme high fatigue resistance to cyclic motion, and noiseless operation. Nitinol has found application in tactile displays which reproduce tactile parameters such as texture and shape, depending on the application. This paper presents the effects of thermal interference between adjacent Nitinol spring actuators in a tactile display. The tactile display is made of a 3 by 3 pin array whose spatial resolution was varied from 4 mm to 6 mm in steps of 1 mm while a current of 1.5 A was used to actuate 8 of the springs, and the centre spring was left unactivated to observe the thermal effects on it due to the heat gradient formed. A Finite Element (FE) model was developed using COMSOL Multiphysics and the results were further verified through experimentation. In both cases, there was visible thermal interference between actuators. The increase in spatial resolution saw a decrease in thermal interference by 12.7%. Using a fan to introduce forced convection, reduced the thermal interference in the simulation by 20% and during experimentation by 11%. The results of this research indicate a spatial resolution of 6 mm reduced the thermal inference to a negligible rate. However, thermal interference could not be eliminated with these two methods.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An Investigation of the Effects of Thermal Interference between Adjacent Nitinol Spring Actuators in a Tactile Display

Sekerere¹,

Ndeda²,

Karanja³

2023

WJET

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“…In our previous work, microelectromechanical system (MEMS)‐type tactile display devices have been developed using a thick‐film SMA actuator array with a pitch of 1–2 mm for vibration vertical to the human skin [16]. At low frequency, the generated amplitude was smaller than 25 μm which was insufficient for stimulation to human skin.…”

Section: Introductionmentioning

confidence: 99%

Fabrication ofShearing‐Motion‐TypeTactile Display Mechanism UsingSMA Thick‐FilmActuators and Coil Springs Array

Sato

Maruyama

Saito

et al. 2023

IEEJ Transactions Elec Engng

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A shearing‐motion‐type microelectromechanical system (MEMS) tactile display mechanism was fabricated to provide a shear vibration stimulus to the fingertip. It consisted of shrinking shape memory alloy (SMA) thick‐film actuators and a supporting coil spring array. The SMA actuator array was designed and fabricated using a flash‐evaporated SMA film (10 μm thick) on a mirror‐polished Cu substrate. The coil spring was successfully arrayed on a glass substrate with an SU‐8 circular array pattern. The glass substrate with the coils was bonded to the SMA substrate to complete the shearing‐motion mechanism. During the bonding process, the SMA actuators were initially elongated by the coil springs. The generated amplitude and force of the fabricated mechanism were characterized when the SMA actuator was heated by applying a pulsed current to be shrank by the shape recovery effect. The fabricated shearing‐motion mechanism successfully generated large amplitude of 41 μm (around 80 μm in reciprocal motion) and force of 22 mN at a driving frequency of 1 Hz. At 20 Hz, an amplitude of 23 μm and force of 10 mN were obtained even though they were reduced owing to the low thermal response. At both driving frequencies, the obtained amplitudes and forces seems to be sufficient for tactile stimulation to finger skin. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

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“…Fewer design configurations have explored Nitinol in its sheet form for tactile actuators. For instance, Xu et al [5] developed a tactile display with meandering Nitinol films glued to a bias spring on one side and pins on the other. In their system heat from an external heater array, changed the shape of the Nitinol film which caused the pin to move on one side.…”

Section: Introductionmentioning

confidence: 99%

Transforming a Monolithic Sheet of Nitinol into a Passive Reconfigurable Tactile Pixel Array Display at Braille Resolution

Bhatnagar¹,

Marquardt²,

Miodownik³

et al. 2021

2021 IEEE World Haptics Conference (WHC)

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Shape changing materials create a unique opportunity to design reconfigurable tactile display actuators. In this paper, we present a method that transforms a single thin monolithic sheet of Nitinol into a passive reconfigurable tactile pixel array at Braille resolution. We have designed a 27x27 tactile pixel array in which each pixel can be selectively actuated with an external source of heat. The pixels rise 0.4mm vertically with a peak blocked force of 0.28kg and have an average blocked force of 0.23kg at room temperature. After cooling, the pixels can be mechanically reconfigured back to their flat state for repeatable actuation. We demonstrate this actuator's interactive capabilities through a novel erasable tactile drawing interface.

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Fabrication and characterization of SMA film actuator array with bias spring for high-power MEMS tactile display

Cited by 11 publications

References 6 publications

An Investigation of the Effects of Thermal Interference between Adjacent Nitinol Spring Actuators in a Tactile Display

An Investigation of the Effects of Thermal Interference between Adjacent Nitinol Spring Actuators in a Tactile Display

Fabrication ofShearing‐Motion‐TypeTactile Display Mechanism UsingSMA Thick‐FilmActuators and Coil Springs Array

Transforming a Monolithic Sheet of Nitinol into a Passive Reconfigurable Tactile Pixel Array Display at Braille Resolution

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