Haptic perception on touchscreens varies across fingers, yet little is known about how finger identity and multi-finger use shape tactile discrimination and user experience. We conducted two experiments with four haptic feedback. In Experiment 1, right-handed participants explored each of the ten fingers individually under stationary and moving conditions. Experiment 2 examined two-finger sequences with same participants. Results showed that moving exploration enhanced accuracy, confidence, and enjoyment, while stationary touch increased cognitive and physical load, especially for weaker fingers such as the left ring and pinky. The right thumb and index consistently performed best. In dual-finger trials, moving exploration improved second-finger performance, and adjacent same-hand pairs (e.g., Left Index–Left Thumb, Right Thumb–Right Index) yielded higher synergy. These findings highlight the role of finger anatomy, motion, and coordination, and provide concrete guidelines on which fingers (or combinations) and exploration modes to assign for haptic surfaces that optimize accuracy, comfort, and engagement.

We investigate the relevance of surface haptic rendering techniques for tactile devices. We focus on the two major existing techniques and show that they have complementary benefits. The first one, called textsc{S}urface textsc{H}aptic textsc{O}bject (textsc{SHO}), which is based on finger position, is shown to be more suitable to render sparse textures; while the second one, called textsc{S}urface textsc{H}aptic textsc{T}exture (textsc{SHT}), which is based on finger velocity, is shown to be more suitable for dense textures and fast finger movements. We hence propose a new rendering technique, called textsc{L}ocalized textsc{H}aptic textsc{T}exture (textsc{LHT}), which is based on the concept of textit{taxel} considered as an elementary tactile information that is rendered on the screen. By using a grid of taxels to encode a texture, textsc{LHT} is shown to provide a consistent tactile rendering across different velocities for high density textures, and is found to reduce user textit{error rate} by up to 77.68% compared to textsc{SHO}.

Tactile devices with ultrasonic vibrations (based on squeeze film effect) using piezoelectric actuators are one of the existing haptic feedback technologies. In this study we have performed two psychophysical experiments on an ultrasonic haptic tablet, in order to find the minimum size of a tactile element on which all the users are able to perfectly identify different types of textures. Our results show that the spatial resolution of the tactile element on haptic touchscreen actually varies, depending on the number and types of tactile feedback information. A first experiment exhibits three different tactile textures, chosen as being easily recognized by users. We use these textures in a second experiment, and evaluate minimal spatial area on which the chosen set of textures can be recognized. Among other, we find the minimal size depends on the texture nature.

This paper presents a method to control ultrasonic waves on a beam, allowing to obtain a Multi-touch ultrasonic tactile stimulation in two points, to give the sensation to two fingers, from two piezoelectric transducers. The multi-modal approach and the vector control method are used to regulate the vibration amplitude, in order to modulate the friction coefficient with the fingers. An analytical modelling is presented, with experimental validation. Finally a psychophysical experiment shows that a multi-touch ultrasonic tactile stimulation is possible.

Ultrasonic vibration of a plate can be used to modulate the friction of a finger pad sliding on a surface. This modulation can modify the user perception of the touched object and induce the perception of textured materials. In the current paper, an elastic model of finger print ridges is developed. A friction reduction phenomenon based on non-Coulombic friction is evaluated based on this model. Then, a comparison with experimental data is carried out to assess the validity of the proposed model and analysis.

Electrovibration and squeeze film effect can modify the perception a user has of a flat surface. These two stimulation principles are compatible, which means that they can be used at the same time on the same tactile stimulator. This paper first highlights the differences between the two principles, then gives experimental results obtained when merging, with specific conditions, these two stimulation principles.

We present Surfpad, a pointing facilitation technique that does not decrease target distance or increase target width in either control or display space. This new technique operates instead in the tactile domain by taking advantage of the ability to alter a touchpad's coefficient of friction by means of a squeeze film effect. We report on three experiments comparing Surfpad to the Semantic Pointing technique and constant control-display gain with and without distractor targets. Our results clearly show the limits of traditional target-aware control-display gain adaptation in the latter case, and the benefits of our tactile approach in both cases. Surfpad leads to a performance improvement close to 9% compared to unassisted pointing at small targets with no distractor. It is also robust to high distractor densities, keeping an average performance improvement of nearly 10% while Semantic Pointing can degrade up to 100%. Our results also suggest the performance improvement is caused by tactile information feedback rather than mechanical causes, and that the feedback is more effective when friction is increased on targets using a simple step function.

Haptic perception of curvature can be achieved by passive or active finger touch. In this study we proposed a new curvature perception haptic device that can independently orient, elevate and translate a flat plate. By exploring it with a finger through active touch, we can render a curved shape. According to the characteristics of this device, two curvature rendering motion models were analyzed: motion model without compensation and motion model with position compensation. Two experiments were then executed. Experiment 1 has verified that our device is able to produce distinct curvatures. Experiment 2 has compared the performances obtained with each motion model during the tasks of curved shape discrimination.