arXiv:submit/5570537 [cs.HC] 6 May 2024

Pinching Tactile Display: A Cloth that Changes Tactile Sensation
by Electrostatic Adsorption
Takekazu Kitagishi

Hirotaka Hiraki

Hiromi Nakamura

The University of TokyoZOZO Research
Tokyo, Japan
ktgs@acm.org

The University of Tokyo
Tokyo, Japan
hiraki-uts1@g.ecc.u-tokyo.ac.jp

The University of Tokyo
Tokyo, Japanhirominakamura@sigchi.org

Yoshio Ishiguro

Jun Rekimoto

The University of Tokyo
Tokyo, Japanishiy@acm.org

The University of Tokyo
Sony CSL Kyoto
Tokyo / Kyoto, Japanrekimoto@acm.org

Pinching tactile display :A fabric with dynamicallychanging tactile sensations.

Provide vibration feedback to the fingers
when rubbed together.

voltagefrequency

Users wear ultra-thin insulated gloves.

Figure 1: Overview of the Pinch Tactile Display. The fabric changes its tactile sensation by manipulating the electrostatic force
between the conductive fabric and the user’s finger. Users interact with it by wearing gloves and rubbing them together. The
texture variation is achieved by adjusting the voltage and frequency, with the voltage modulated by the power supply andthe frequency controlled by Arduino. The inherent thinness and softness of the fabric allows for a natural touch experience,enhancing immersive interactions in virtual reality environments.

ABSTRACT
Haptic displays play an important role in enhancing the sense ofpresence in VR and telepresence. Displaying the tactile properties offabrics has potential in the fashion industry, but there are difficulties
in dynamically displaying different types of tactile sensations while
maintaining their flexible properties. The vibrotactile stimulationof fabrics is an important element in the tactile properties of fabrics,
as it greatly affects the way a garment feels when rubbed against
the skin. To dynamically change the vibrotactile stimuli, many
AVI 2024, June 3–7, 2024, Arenzano, Genoa, Italy© 2024 Copyright held by the owner/author(s).
This is the author’s version of the work. It is posted here for your personal use. Not
for redistribution. The definitive Version of Record was published in International
Conference on Advanced Visual Interfaces 2024 (AVI 2024), June 3–7, 2024, Arenzano,
Genoa, Italy, https://doi.org/10.1145/3656650.3656690.

studies have used mechanical actuators. However, when combinedwith fabric, the soft properties of the fabric are compromised by thestiffness of the actuator. In addition, because the vibration generated
by such actuators is applied to a single point, it is not possible toprovide a uniform tactile sensation over the entire surface of thefabric, resulting in an uneven tactile sensation. In this study, we
propose a Pinching Tactile Display: a conductive cloth that changes
the tactile sensation by controlling electrostatic adsorption. By
controlling the voltage and frequency applied to the conductive
cloth, different tactile sensations can be dynamically generated.
This makes it possible to create a tactile device in which tactile
sensations are applied to the entire fabric while maintaining thethin and soft characteristics of the fabric. As a result, users could
experiment with tactile sensations by picking up and rubbing the

AVI 2024, June 3–7, 2024, Arenzano, Genoa, Italy

Takekazu Kitagishi, Hirotaka Hiraki, Hiromi Nakamura, Yoshio Ishiguro and Jun Rekimoto

fabric in the same way they normally touch it. This mechanism has
the potential for dynamic tactile transformation of soft materials.

reduces the uniform weave of the cloth and the property that theentire cloth has a uniform tactile feel to some extent.
In this paper, we propose a Pinching Tactile Display, a cloththat changes tactile sensation by electrostatic adsorption. It has a
CCS CONCEPTS• Hardware → Sensors and actuators; Haptic devices; Electro-mechanical mechanism to transform the tactile sensation by controlling theelectrostatic force between the conductive fabric and the finger
devices; Emerging interfaces; • Computer systems organizawithout using a mechanical actuator. It inherits the thin and softtion → Sensors and actuators; • Human-centered computing
property of the cloth. It has uniform tactile sensations over the→ Haptic devices; Mixed / augmented reality; Virtual reality.
whole cloth, which allows us to obtain tactile sensations by pinching
and rubbing the cloth as we normally do when testing the feel of
KEYWORDS
the cloth. This increases the reality of how we interact with the
Haptic Display, Textiles, Soft Actuators, Personal Fabrication
fabric.
Users wear ultra-thin insulated gloves and touch the conductive
ACM Reference Format:
Takekazu Kitagishi, Hirotaka Hiraki, Hiromi Nakamura, Yoshio Ishiguro,fabric to prevent electric shock and to feel the delicate tactile sensaand Jun Rekimoto. 2024. Pinching Tactile Display: A Cloth that Changes
tions of the cloth. Users can experience multiple tactile sensations
Tactile Sensation by Electrostatic Adsorption. In International Conference onof cloth with a single device. We confirmed that this mechanism
Advanced Visual Interfaces 2024 (AVI 2024), June 3–7, 2024, Arenzano, Genoa,
changes the tactile sensation of the fabric. We also confirmed that
Italy. ACM, New York, NY, USA, 9 pages. https://doi.org/10.1145/3656650.
different tactile sensations can be generated by switching the volt3656690
age and frequency.
Our contributions include the following:

1

INTRODUCTION

Haptic displays play an important role in enhancing the senseof presence in VR and telepresence. They enhance the realism ofobjects by presenting the texture of objects that are distant or outof place. As a result, it can improve the sense of presence andimmersion when manipulating virtual reality spaces and create asense of trust in remote objects.
In order to improve the sense of presence in VR and telepresence scenarios, attempts have been made to represent the tactile
sensations of various objects around us in our daily lives. In theprocess of trying to reproduce the tactile sensations of such everyday objects, reproducing the tactile sensations of soft objects ischallenging because the shape of soft objects can be changed moreeasily by pushing or pulling than that of hard objects.
Therefore, the aim of this study is to present the tactile sensation of soft cloth. Cloth is used daily for clothing, bedding, sofas,
chairs, etc. The tactile sensation of these materials is something
we experience on a daily basis, and if it can be changed according
to an individual’s preferences, it is expected to make the individual’s daily life more comfortable. Therefore, the presentation of soft
fabric tactile sensations can be expected to have an impact on the
fashion and furniture industries. For example, if online shoppers
can check the feel of a product before purchasing it, it will reduce
the experience of the purchased product not feeling like what theywanted to wear, thereby improving the quality of online shopping.
The vibrotactile stimuli that people feel when the fabric rubs
against their skin are important to the texture of the fabric. Whencreating a device that dynamically changes and presents vibrotactile sensations, it is common to use vibration generated by amechanical actuator such as a motor [4, 17]. However, when a mechanical actuator is applied to cloth and a mechanical actuator isused to generate the vibration stimulus produced when the cloth ispicked up and rubbed with the fingers, the softness of the cloth isreduced because the actuator itself is stiff. In addition, the vibration
generated by the mechanical actuator attenuates as it moves awayfrom the area being vibrated, making it impossible to provide a
uniform tactile sensation over the entire surface of the cloth. This

• We have developed a technique that allows us to change thetactile feel of the cloth while maintaining its thin and soft
nature.
• It allows users to pinch and rub the conductive fabric tocheck its tactile feel, just as they would normally check thetactile feel of a fabric.
• By controlling the voltage and frequency of the electricity
applied to the conductive cloth, we can dynamically change
the tactile feel of the cloth.

2 RELATED WORK
2.1 Haptic Display for Hard objects
The most common method of tactile transmission is the presentation of vibration by mechanical vibration. [4, 17] introduced eccentric rotating mass motors, [12, 17] introduced voice coils, [3]introduced piezo electric actuators to represent the texture of fabrics. However, when combined with fabric, the soft properties of thefabric are compromised by the stiffness of the actuator. In addition,
because the vibration generated by such actuators is applied to asingle point, it is not possible to provide a uniform tactile sensation
over the entire surface of the fabric, resulting in an uneven tactile
sensation.
There is a study that uses a touch panel to convey the tactile sensation of the fabric while complementing it with visuals. TPaD [19]and ShiverPaD [5] is based on the theory, design and constructionof tactile displays that create texture sensations through changes
in surface friction, known as the squeeze film effect. Using ultrasonic frequency and low amplitude vibrations between two flat
plates, a squeezed film of air is created between the surfaces, reducing friction. TeslaTouch [2] is a technique for creating virtual
textures by controlling the shear force on a touch panel. It involves
a simple structure where high voltage is applied and an insulator isplaced between the user and the panel, creating a shear force whentouched. This allows the creation of thin devices that can change
their feel when rubbed together. However, despite its simplicity,
TeslaTouch targets touch panels that are inherently hard, creatingPinching Tactile Display: A Cloth that Changes Tactile Sensation
by Electrostatic Adsorptiona

AVI 2024, June 3–7, 2024, Arenzano, Genoa, Italyb

Conductive ClothDC
power source
Boosterof
Voltage

Resistor 1

Transistor
Figure 2: Principle of the Pinching Tactile Display. (a) Without Voltage (b) With Voltage. Applying a voltage to a conductive fabric creates a charge distribution that generates
an electrostatic force on the skin and a frictional force. By
periodically varying the frictional force, the skin in contact
is periodically deformed. As a result, the user feels vibratory
stimulation.

challenges in accurately representing the feel of the material whenrubbed together. The touch panel is hard, which limits its ability toconvey the soft tactile sensation of the fabric.

2.2

Haptic Display for Soft Objects

One way to present soft tactile sensations is to change the shape ofsoft objects. [9] uses the attraction between ferromagnetic yarns
and permanent magnets seamlessly integrated into knitted fabrics
to provide a passive tactile sensation. In addition, [6] provides tactile
sensations by 3D scanning the surface structure of fabrics and 3D
printing the same structures. They envision controlling the shapeof a soft object and combining it with vision to provide a soft tactile
sensation, but only one type of tactile sensation can be presented
with a single device, the device takes time to create, and the tactile
sensation cannot be dynamically changed.
Some research displays tactile sensations of soft objects by allowing the user to touch a real piece of fabric. HapticRevolver [16]is an actuator wheel that rises under the finger and makes contact
with a virtual surface. Haptic Palette [7] extends this wheel-based
actuator with visual enhancements on top of the physical texture
in virtual reality environments, allowing the user to experience
mixed material perception. Telextiles [8] uses a roller-type device
to present the closest tactile match to a remote fabric. These devices
are limited in the number of fabrics that can be attached to them,and the tactile sensation of the fabrics does not change continuously
and therefore cannot be dynamically changed.
Ultrasonic [14, 18] can display and dynamically change the tactile
sensation of soft objects. However, they often require expensive
or large equipment and are not suitable for the purpose of easily
experiencing the tactile sensation of soft objects.
In view of the above, this study proposes a mechanism to dynamically change the tactile sensation of soft cloth without using
expensive or large-scale devices.

Pulse Generator

Resistor 2

Figure 3: System Overview. When the switch is turned on,
current flows, causing a voltage drop across Resistor 1, resulting in 0V across the Conductive Cloth. Conversely, when theswitch is off, no current flows, resulting in no voltage drop
across Resistor 1 and a high voltage across the Conductive
Cloth. The switching mechanism is controlled by the pulse
generator and a transistor. The switch is activated (turnedon) when voltage is applied to the transistor and deactivated(turned off) when no voltage is applied. This configuration allows a periodic voltage to be applied to the conductive cloth.

2.3

Electrovibration

Electrovibration is a phenomenon that allows us to create tactile sensations by controlling the electrostatic friction between a dielectricmaterial and the user’s fingers. The discovery of electrovibration
dates back to 1954, when it was discovered by accident. Mallinckrodt et al. reported that dragging a dry finger across a conductive
surface covered with a thin insulating layer and stimulated with a
110 V signal resulted in a characteristic “rubbery” sensation [10].
This sensation was explained by the theory that the insulating layerof the dry outer skin acts as the dielectric layer of a capacitor. In
this model, the conductive surfaces and fluids within the finger
tissue represent the two opposing plates of the capacitor. While
this force is too weak to be felt when the finger is static, it significantly modulates the friction between the surface and the skin of
the moving hand, creating the unique rubbery sensation associatedwith electrovibration.

3

SYSTEM CONFIGURATION

We propose Pinching Tactile Display, a cloth that changes tactile
sensation by electrostatic adsorption. By changing the voltage andfrequency of the square wave applied to the conductive cloth, we
can control the electrostatic adhesion force between the cloth andthe finger to generate multiple tactile sensations of the cloth. The
user puts on the gloves and rubs his or her fingers against thecloth. They can experience multiple tactile sensations with a single
device. The gloves are ultra-thin, non-conductive and act as an

AVI 2024, June 3–7, 2024, Arenzano, Genoa, Italy

insulator, preventing electricity from flowing from the fabric to
the fingers while minimizing the space between the fingers andthe fabric, allowing the user to feel the subtle tactile sensationsof the fabric. We can adjust the voltage applied to the conductive
fabric by adjusting the power supply voltage, and the frequency bycontrolling the switching operation of the transistors. This systemprovides tactile sensation throughout the conductive cloth while
maintaining the thin and soft characteristics of the cloth. As a result,users can explore the tactile sensation by pinching the cloth andrubbing it, as they normally do when touching cloth.

3.1

Principle of Pinching Tactile Display

Figure 2 illustrates the principle of the Pinch Tactile Display, whichuses the phenomenon of electrovibration. This display consists ofa conductive cloth and an insulator, such as a PVC glove. We connected the conductive fabric to a high voltage supply. Without highvoltage, no external force is applied to a finger moving over thetactile display. Consequently, the user perceives the original surface of the conductive cloth, as shown in Figure 2(a). When voltage
is applied to the conductive cloth, the finger becomes negatively
charged, while the conductive cloth connected to the high voltage becomes positively charged. This charge distribution creates
an electrostatic force on the skin, resulting in a frictional force,as shown in Figure 2(b). By periodically changing the frictional
force, the contacting skin deforms periodically. As a result, the user
perceives a vibratory stimulus.
The attractive force and the resulting frictional force can be
succinctly expressed as follows:
𝜖𝜖0 𝑉 (𝑡) 2
(1)
𝐹 =𝐴
2
𝑑


𝜖𝜖0 𝑉 (𝑡) 2
𝐹 ′ = 𝜇𝐹 = 𝜇𝐴(2)2𝑑where 𝐹 is the attractive force, 𝐹 ′ is the frictional force, 𝜖0 is thevacuum permeability, 𝜖 is the relative permeability of the insulator,
𝐴 is the contact area, 𝑉 (𝑡) is the applied voltage, 𝑑 is the thicknessof the insulator, and 𝜇 is the coefficient of friction. This equation implies that the voltage, the time period (frequency), and the distance
between the finger and the conductive cloth significantly affect theelectrostatic friction.

3.2

Controlling Tactile Sensation of ClothThis system alters tactile sensations by varying the magnitude andfrequency of the square-wave voltage applied to the conductive
cloth. The proposed mechanism varies the voltage applied to the
Conductive Cloth by changing the voltage of the DC power source
input to the Voltage Booster. The voltage on the Conductive Clothchanges depending on the voltage output by the DC power source
and the function by which the Booster of Voltage transforms the
input voltage into an output voltage.
The proposed mechanism uses the switching action of a transistor to adjust the on/off state of the voltage connected to the
conductive cloth, thereby applying a voltage in the form of squarewaves. The switching of the transistor is controlled by a pulse generator. When the pulse generator applies voltage, the switch turns
on; when no voltage is applied from the pulse generator, the switch

Takekazu Kitagishi, Hirotaka Hiraki, Hiromi Nakamura, Yoshio Ishiguro and Jun Rekimototurns off. When the switch is on, a high voltage increased by thevoltage booster is applied to the conductive cloth; when the switch
is off, no voltage is applied to the cloth. By equalizing the on andoff times, square waves are generated. The frequency of the voltage
applied to the Conductive Cloth changes according to the durationof the on and off states of the switch.

3.3

Conductive Fabric and Thin Glove forInsulator

The user wears gloves to minimize the distance between the fingers
and the fabric while preventing electricity from flowing from thefabric to the fingers. As shown in the equation 2, distance is an
important factor that is the square of the equation, and the thinnessof the material is an important factor in sensing tactile changes.
Thin gloves also allow the wearer to feel the subtle tactile sensationsof the material. By using the method of putting on the gloves first,
the user can finish feeling the insulator before touching the fabricand can concentrate on the feel of the fabric. In addition, the gloves
are relatively close to the fingers and do not interfere much withthe feel of the fabric. Because any thin, insulating material can beused, they are inexpensive, widely available, and easy to obtain.
To ensure that the voltage spreads evenly over all areas, weused a conductive fabric made of 100% metal fibers with a uniform
surface structure. Like typical fabrics, it has the characteristics ofbeing thin and flexible.

3.4

Safety Measures

For safety, the current flowing through the high-voltage part of thetactile device and the circuit connected to it was set very low. The
current flowing in the high-voltage section was limited to 0.5 𝑚𝐴or less, which is considered safe for the human body [15]. This
amount of current is said to be the same as the amount of current
that flows through a user’s hand when using a capacitive touch
screen used in a typical smartphone [1].

4

EVALUATION

To evaluate whether we could realize a cloth that changes its tactile
sensation, we conducted a user test. We investigated whether thedevice’s tactile sensation changes by controlling the electrostaticadhesion force and whether the fabric maintains its softness andflexibility even when the tactile sensation changes.
The hypotheses are as follows:
H1 The magnitude of the electrostatic force, which pulls the user’s
finger towards the cloth, varies with the voltage, and thefrequency of this pulling force changes with the frequencyof the applied signal. Therefore, by switching the voltage
and frequency, users can perceive different tactile sensations
from the device.
H2 Since no rigid structures are used for the vibration of the cloth,
when a person touches the cloth, the properties of the cloth
remain unchanged, and only the tactile sensations related toelectrovibration change.

Pinching Tactile Display: A Cloth that Changes Tactile Sensation
by Electrostatic Adsorption

Pinching Tactile Display
Power
SupplyMOS-FET
DC-DC
converter

AVI 2024, June 3–7, 2024, Arenzano, Genoa, Italy

Detailed Property of the Tactile Sensation. To confirm the propertyof the tactile sensations displayed, we asked subjects two questions.
First, for all 10 states of the cloth, we asked subjects to touch thecloth and freely describe their impression of the tactile sensationof the cloth. Second, they touched the cloth and answered a fivepoint Likert Scale for the four properties: roughness, thickness,
stiffness and warmth. Our choice of descriptive term pairs relates
to the findings of Soufflet, Calonnier and Dacremont [11] who
demonstrate that the most significant scales their participants used
to rate the properties of textiles were Stiff-Flexible, Thick-Thinand Soft-Harsh. We calculated the average of the answers for eachindex for each state of the cloth and visualized to interpret what
the respective trends were.

4.2
ArduinoFigure 4: System setup for evaluation. The system consists ofa conductive cloth, a DC-DC converter for booster of voltage,a MOS-FET for transistor, Arduino for pulse generator and apower supply.

4.1

Displayed Tactile sensation

To verify (H1) people can feel different sensations from the device byswitching the voltage/frequency, we changed the voltage/frequency
applied to the cloth and had subjects touch it. We then asked thesubjects whether they display different tactile sensations, how theychanged with voltage and frequency respectively and what thesesensations were like.
We changed the voltage between 100 𝑉 , 200 𝑉 and 300 𝑉 and thefrequency between 50 𝐻𝑧, 100 𝐻𝑧 and 200 𝐻𝑧. Each of these wascombined to create a total of 3 × 3 = 9 different states. Then we
asked subjects in a total of 10 different states: nine of these and one
in which no electricity was applied.
Change in Tactile Sensation. To check whether this device display
different tactile sensations, we asked users how many different
tactile sensations they felt after touching the cloth in all states. In
order to obtain statistics on how many different tactile sensations
were felt out of a total of nine, we calculated the mean and varianceof the types of responses given.
Effects of Voltage and Frequency on Tactile Sensation. To ascertain
how their tactile sensations changed with the respective changes
in voltage and frequency, we analysed statistically the Likert Scaleanswers. To determine which voltage, frequency or their alternating factors had a predominant effect on the tactile properties of thecloth, we analysed the responses obtained for a total of 3 × 3 = 9
different states, combining three types of voltage (100 𝑉 , 200 𝑉 and
300 𝑉 ) and three types of frequency (50 𝐻𝑧, 100 𝐻𝑧 and 200 𝐻𝑧).
Since this obtained data are a two-factor within-participant design
with a within-participant factor (voltage) × within-participant factor (frequency), and since normality cannot be assumed for thedata obtained, we applied an aligned rank transform (ART) andconducted a two-way ANOVA [20].

Properties as ClothTo test the hypothesis (H2) the properties of the fabric remainunchanged even when the electrostatic force is controlled, we varied
the voltage and frequency applied to the fabric, as we did in theprevious chapter. For each condition, we asked participants whether
the tactile sensation of the fabric was acceptable and what type offabric the tactile sensation resembled.
Is It Acceptable as a Cloth? Regarding the acceptability of thetactile sensation as a fabric, we hypothesized that the tactile sensation would be acceptable when the voltage was low, and that the
impression of electricity would become stronger and the impression of the fabric would become weaker when the voltage was high.
After touching the fabric in each state, we asked participants if thetactile sensation was acceptable as a fabric or if they felt that the
fabric had lost its texture. We calculated the mean and variance ofthe number of acceptable states out of the 10 states of the fabric.
Tactile Similarity to Familiar Cloth. Regarding the similarity ofthe presented tactile sensation to the tactile sensation of a fabric,
we hypothesized that it would be similar to the tactile sensationof a fabric with increased friction compared to the original conductive fabric. We selected 16 types of fabrics from a fabric sample
book [13], carefully choosing fabrics with different materials andfolding methods to ensure a variety of textures. As before, we created 10 states of the conductive cloth by applying electricity to it.
For each state, we asked the participants to select the fabric thatwas most similar in tactile sensation from among the 16 types offabrics. This was done for each participant individually. Next, we
tallied and visualized how many times each of the 16 fabrics was
selected. We also tallied and visualized how many times each typeof tissue was selected for each voltage and frequency category.
Through these processes, we considered the characteristics of thefabrics for which similar tactile sensations could be produced withthis system.

4.3

System Setup

The experimental setup focuses on a system designed to control
electrostatic forces on a conductive cloth. The system is designed
to generate tactile sensations by manipulating electrostatic forces
through variable voltage and frequency inputs.The core componentof our system is the conductive cloth, which is essential for applying the desired voltages. We used a conductive cloth measuring

AVI 2024, June 3–7, 2024, Arenzano, Genoa, Italy

Table 1: Criteria cloth and their properties.

a

b

c

Figure 5: Experimental procedure. (a) Subjects answered questions about the tactile sensation of the conductive cloth. (b)Subjects selected the most similar tactile sensation cloth
among the 16 prepared fabrics. (c) Subjects answered a 5point Likert scale for roughness, thickness, stiffness, andwarmth based on four fabrics: jeans, voile, gauze, and towels.

approximately 30 𝑐𝑚 × 30 𝑐𝑚, made of 100 % silver fiber, with anelectrical resistance of 1 ohm and an electromagnetic shielding effectiveness of 60DB. The cloth is knitted to provide elasticity, witha weight of 90 𝑔/𝑚 2 and a thickness of 0.232 𝑚𝑚.
To control the electrostatic force, the system uses Arduino to
generate square waves at 50 𝐻𝑧, 100 𝐻𝑧 and 200 𝐻𝑧 in the rangeof 0V to 5V. A MOS-FET is used to turn off at 0V and turn on
at 5V. This setup allows the conductive fabric to be subjected to
100 𝑉 , 200 𝑉 and 300 𝑉 when the switch is on and 0V when it
is off, thereby applying square wave voltages to the conductive
fabric at the voltage and frequency. The MOSFET model used isthe silicon N-channel MOS (DTMOS-H) TK31N60X. The system
also includes Arduino UNO, a DC-DC converter (EMCO G03) and apower supply from Matsusada. The specific resistors and currents
used in the system are yet to be determined.
In addition to the conductive fabric, ultra-thin insulating gloves
were used in the experiments. These gloves are made of polyvinyl
chloride (PVC) with a thickness of 0.035 𝑚𝑚, measured with amicrometer. The gloves are powder-free on the inside and measure
23.5 𝑐𝑚 ×10.5 𝑐𝑚 ×8.5 𝑐𝑚. This setup allows a controlled interaction
between the user’s skin and the electrostatically charged fabric,
allowing a detailed study of the tactile sensations produced bydifferent electrostatic conditions.

4.4

Takekazu Kitagishi, Hirotaka Hiraki, Hiromi Nakamura, Yoshio Ishiguro and Jun Rekimoto

Experimental Procedure

We conducted a user study with six participants, five men and
one woman, all in their twenties. We conducted all experiments

ROUGH

NEUTRALSMOOTH

Jeans

Voile

Gauze

STIFF

NEUTRALFLEXIBLE

Towelling

Gauze

Voile

THICK

NEUTRAL

THIN

Jeans

Towelling

Gauze

WARM

NEUTRAL

COOL

Towelling

Jeans

Voile

in accordance with the safety standards approved by the Ethics
Research Committee of our institute. We explained the experiment
to the participants prior to their participation, and they signed
informed consent forms. In addition, we conducted the study inaccordance with the ethical standards of the Declaration of Helsinki.
Subjects answered the following question A about the tactile
sensation of the cloth without prior application of electricity. The
reason for having them touch the cloth first was to confirm theproperties of the original conductive cloth by touch and then use
it as a basis for the tactile sensation when electricity was applied.
Next, three types of voltage (100 𝑉 , 200 𝑉 , and 300 𝑉 ) and three
types of frequency (50 𝐻𝑧, 100 𝐻𝑧, and 200 𝐻𝑧) were used to create
a total of 3 × 3 = 9 types of conductive cloth. For each type, theparticipants answered question A about the tactile sensation of
the cloth. To eliminate the influence of the order of touching andthe tactile impression of the previously touched cloth, the orderin which the cloth was presented in each state was randomized.
Finally, participants were asked how many of the nine tactile sensations they thought were manifested in the nine tactile sensations
presented.
Question A asks about the tactile sensation of the cloth in eachcondition and consists of four questions: roughness, thickness, hardness, and warmth, each answered on a 5-point Likert scale, "yes"or "no" answer if they can accept the cloth as tactile free answerof how they feel when they touch the cloth, selection of the mostsimilar tactile sensation cloth among the 16 prepared fabrics.
Respondents were asked to answer on a 5-point Likert scale forroughness, thickness, stiffness, and warmth. To reduce the influenceof individual differences in responses, they were asked to answer
based on four fabrics: jeans, voile, gauze, and towels. Four fabrics
were selected for the study. All were 100% cotton and were familiar
to the participants because of their common use. Each criterion
was developed as shown in the Table 1. Subjects compared eachcriterion by touching the fabric and the conductive fabric and wrote
down the most appropriate score.
For the similar fabrics question, the 16 fabrics are: 1: Marquisette,
2: Cashmere, 3: Satin, 4: Milanese, 5: Faille, 6: Viyella, 7: Metallic
Tone Cloth, 8: Georgette, 9: Dungaree, 10: Quilting, 11: Paisley, 12:
Velveteen, 13: Chenille, 14: Cambric, 15: Cord Weave, 16: Blister
Cloth. Subjects touched each fabric and the conductive fabric andselected the one they felt was most similar.

Pinching Tactile Display: A Cloth that Changes Tactile Sensation
by Electrostatic Adsorption

AVI 2024, June 3–7, 2024, Arenzano, Genoa, Italy

Table 2: Results of the statistical analysis.
roughness

stiffnessthickness

warmthTerm

P valueTerm

P valueTerm

P valueTerm

P value

VoltageFrequency
Voltage × Frequency

7.76 × 10 −5

VoltageFrequency
Voltage × Frequency

0.317
0.281
0.813

VoltageFrequency
Voltage × Frequency

0.044
0.958
0.901

VoltageFrequency
Voltage × Frequency

0.086
0.085
0.801

4.5

0.263
0.777

ResultThrough these experiments, we have confirmed that this devicechanges the tactile sensation by controlling the electrostatic adsorption force, and that even if the tactile sensation changes, thesoftness and flexibility as a cloth are maintained to some extent.
For the tactile sensation, we investigated in detail whether the tactile sensation changed, the effects of voltage and frequency on thetactile sensation, and the characteristics of the presented tactile
sensation. For the cloth properties, we investigated whether it was
acceptable as a cloth and what kind of cloth it resembled.
4.5.1

Displayed Tactile Sensation.

Change in Tactile Sensation. From the experiment, we found thatthe tactile sensations generally changed when the voltage and frequency were changed; of the nine tactile sensations displayed, thesubjects responded that they felt an average of seven different tactile sensations. The reason why all the participants did not perceive
any of the nine tactile sensations may be because they judged thelow voltage of 100 V to be the same as that of the original cloth.
Effects of Voltage and Frequency on Tactile Sensation. Table 2
shows the results. We found that voltage has a statistically significant effect on roughness. In other conditions, voltage and frequency
and their interaction are not statistically significant. However, thep-value for voltage on thickness and the p-value for frequency onheat are somewhat low, suggesting that voltage may have someeffect on thickness and frequency may have some effect on heat.
Detailed Property of the Tactile Sensation. Figure 6 shows the average of the Likert scale responses for roughness, stiffness, thickness,
and warmth for each of the nine states where voltage was applied
to each characteristic. It can be seen that voltage tends to affectroughness, stiffness, and thickness. On the other hand, frequency
tends to have little effect on roughness, stiffness, thickness, andwarmth.
Free response also confirms that the tactile sensations presented
by the system tend to be of varying roughness, hardness, and thickness with voltage: at 100 V, "light and soft," "kind of slippery, smoothand very soft," "feels like silk," "smooth," "soft," smooth and cool,"not much different from the first cloth. Back to the beginning; at
200V it felt tight and rubbery. Feels thicker. Rough". A little rough.
The responses for 300 V were rough, "Very rough," "The roughness
has increased considerably," "Feels like ribbon fabric," and "Thickand hard.
4.5.2

Properties as Cloth.

Is It Acceptable as a Cloth? All six subjects indicated that thetactile sensations were acceptable as cloth tactile sensations, except

for the 300V, 50Hz, 300V, 200Hz condition. This indicates that thesystem is capable of presenting multiple tactile sensations while
generally maintaining the tactile sensation of cloth. On the other
hand, two subjects responded that the tactile sensation of the cloth
was unacceptable at 300 V, 50 Hz and 300 V, 200 Hz. In their freeresponses, at 300 V, 50 Hz, "It was the most vibrating I’ve ever felt
when I stroked it" and "’crackling’"; at 300 V, 200 Hz, "The electricalvibration was so strong that it didn’t feel like a fabric. It felt likepolyester. The responses were as follows. It is believed that thecharacteristics of electrostatic adsorption were felt more strongly
than the characteristics of the fabric, and were not accepted as thetactile sensation of the fabric.
Tactile Similarity to Familiar Cloth. Figure 7 shows the distribution of the number of times the cloth was selected as the mostsimilar. 3, 4, 5, 6, and 9 were selected most often, and these are all
fabrics that were also selected when the original fabric was notelectrified. This indicates that many respondents indicated that the
texture was similar to the original cloth. It can also be seen thatas the voltage is increased, more fabrics with a strong coarseness,such as 14, are selected. This indicates that the presented tactile
impression is strongly influenced by the original cloth, but as thevoltage is increased, the roughness changes to become stronger, and
it is even possible to present a tactile impression that is different
from that of the original cloth. On the other hand, fabrics such
as 2, 7, and 10, which were not selected, had a characteristicallyhigh weave height. The conductive fabrics used in this study weresmooth, and those with many folds and a strong roughness may
have been difficult to express.

5

DISCUSSION

Pinching Tactile Display can dynamically change the tactile sensation of a cloth, and the user can experience multiple tactile sensations with a single device. User tests show that the roughnesschanges mainly by voltage, the soft and flexible nature of the cloth
is maintained, and the tactile sensation of the original conductive
cloth is retained, but by increasing the voltage, a tactile sensationdifferent from the original can be presented. While this system
has the potential to remotely verify the tactile qualities of fabrics
when buying clothes online, or to be used for interactions in virtual
reality spaces to enhance the immersive experience, there is someroom for improvement in our system.
The need to wear gloves is cumbersome to experience the system.
The gloves used in this study are thin, inexpensive, widely available,
and easy to obtain, but not everyone has easy access to such gloves.
It is necessary to lower the voltage or substitute another insulator

AVI 2024, June 3–7, 2024, Arenzano, Genoa, Italy

Takekazu Kitagishi, Hirotaka Hiraki, Hiromi Nakamura, Yoshio Ishiguro and Jun Rekimoto

Figure 6: Distribution of means of Likert scale responses for each voltage and frequency.

might have allowed for a more purely tactile investigation. The
number of subjects was six, and the robustness of the results may
be questionable. These are the next points to be verified.
To increase the expressiveness of this device, the creation of
specific conductive patterns within the fabric should be explored.
This approach would involve designing and integrating different
conductive patterns into the fabric, which could then interact withelectrostatic forces to produce different tactile effects.

6

Figure 7: Distribution of the number of times selected as themost similar fabric.

so that the user can touch and feel the system without wearing
gloves.
It is possible to increase the roughness of tactile sensations with
our system, but reducing it is a challenge. This suggests that starting with a conductive fabric that inherently has a higher level ofroughness may be more advantageous for achieving a wider rangeof tactile sensations. By selecting such a fabric as the base material,
we could potentially improve the system’s ability to simulate awider range of textures. In terms of waveform manipulation, ourstudy focused primarily on square waves. However, the potential
impact of other waveforms, such as sawtooth waves, on tactile sensations remains an area ripe for investigation.Different waveforms
may produce different tactile effects, providing a new method forfine-tuning the tactile experience. Exploring these waveforms could
lead to more nuanced control over the tactile sensations generated
by the system.
There are several things we were not able to explore in this experiment. For example, the gloves may have prevented the subjects
from feeling more delicate tactile sensations than when touchingwith bare hands. Touching the object with the visuals blocked

CONCLUSION

In this paper, we proposed Pinching Tactile Display, a cloth thatchanges tactile sensations by electrostatic adsorption. This device
can display different tactile sensations of different cloths in one
device while maintaining its soft and flexible property. Users can experience multiple tactile sensations with a single device. In addition,
this system provides tactile sensation throughout the conductive
cloth, so users can explore the tactile sensation by pinching andrubbing the cloth as they normally do when touching cloth. The
user test shows that the roughness is mainly changed by the voltage, the soft and flexible nature of the cloth is maintained, and thetactile sensation of the original conductive cloth is maintained, but
by increasing the voltage, a tactile sensation different from the original can be displayed. In the future, we aim to use this technology
to enhance human interaction with fabrics in applications ranging from online shopping and wearable technology to immersive
virtual reality experiences.

ACKNOWLEDGMENTS
This work was supported by JST Moonshot R&D Grant JPMJMS2012,
JPNP23025 commissioned by the New Energy and Industrial Technology Development Organization (NEDO), and ZOZO NEXT, Inc.

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