Generating Clear Vibrotactile Cues with Magnets Embedded in a Soft Finger Sheath

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Research Overview

Natural Embodied Touch

Finger-Surface Contact Mechanics in Diverse Moisture Conditions

Perceptual Integration of Contact Force Components During Fingertip Sliding

Material Intelligence of Animal Whiskers

Artificial Touch Sensing and Processing

Giving Touch to Soft Robot Fingertips Using Vision, Audio and Machine Learning

Capturing and Recognizing Multimodal Surface Interactions

Multimodal Puncture Detection for Urgent Percutaneous Therapies

Haptic Actuation

Quantifying the Quality of Haptic Interfaces

Shape-Changing Haptic Interfaces

Generating Clear Vibrotactile Cues with Magnets Embedded in a Soft Finger Sheath

Salient Full-Fingertip Haptic Feedback Enabled by Wearable Electrohydraulic Actuation

Cutaneous Electrohydraulic (CUTE) Wearable Devices for Pleasant Broad-Bandwidth Haptic Cues

Modeling Finger-Touchscreen Contact during Electrovibration

Perception of Ultrasonic Friction Pulses

CAPT Motor: A Two-Phase Ironless Motor Structure

Immersive Teleoperation

4D Intraoperative Surgical Perception: Anatomical Shape Reconstruction from Multiple Viewpoints

Visual-Inertial Force Estimation in Robotic Surgery

Enhancing Robotic Surgical Training

AiroTouch: Naturalistic Vibrotactile Feedback for Large-Scale Telerobotic Assembly

Optimization-Based Whole-Arm Teleoperation for Natural Human-Robot Interaction

Human-Robot Interaction

Enhancing HRI through Responsive Multimodal Feedback

Haptic Empathetic Robot Animal (HERA)

How does HuggieBot compare to a human hugging partner?

HuggieBot: Evolution of an Interactive Hugging Robot with Visual and Haptic Perception

Human Movement

Reconstructing Sign-Language Movements from Images and Bioimpedance Measurements

Advancing Gait-Retraining Techniques

Multimodal Sensing Reveals the Dynamics of Time-Constrained Teamwork

Previous HI Projects

Finger-Surface Contact Mechanics in Diverse Moisture Conditions

Computational Modeling of Finger-Surface Contact

Perceptual Integration of Contact Force Components During Tactile Stimulation

Dynamic Models and Wearable Tactile Devices for the Fingertips

Novel Designs and Rendering Algorithms for Fingertip Haptic Devices

Dimensional Reduction from 3D to 1D for Realistic Vibration Rendering

Prendo: Analyzing Human Grasping Strategies for Visually Occluded Objects

Learning Upper-Limb Exercises from Demonstrations

Minimally Invasive Surgical Training with Multimodal Feedback and Automatic Skill Evaluation

Efficient Large-Area Tactile Sensing for Robot Skin

Haptic Feedback and Autonomous Reflexes for Upper-limb Prostheses

Gait Retraining

Modeling Hand Deformations During Contact

Intraoperative AR Assistance for Robot-Assisted Minimally Invasive Surgery

Immersive VR for Phantom Limb Pain

Visual and Haptic Perception of Real Surfaces

Haptipedia

Gait Propulsion Trainer

TouchTable: A Musical Interface with Haptic Feedback for DJs

Exercise Games with Baxter

Intuitive Social-Physical Robots for Exercise

How Should Robots Hug?

Hierarchical Structure for Learning from Demonstration

Fabrication of HuggieBot 2.0: A More Huggable Robot

Learning Haptic Adjectives from Tactile Data

Feeling With Your Eyes: Visual-Haptic Surface Interaction

S-BAN

General Tactile Sensor Model

Insight: a Haptic Sensor Powered by Vision and Machine Learning

Haptic Intelligence Members Publications

Generating Clear Vibrotactile Cues with Magnets Embedded in a Soft Finger Sheath

20241113 haptic intelligence 120 cropped — Two magnets embedded in a silicone-rubber sheath worn on a fingertip. Under an alternating magnetic field, the user feels a strong, clear vibration due to excellent mechanical coupling.

This project aims to understand human perception of vibrations applied by a new wearable tactile device [

] that is driven by sound recordings via a nearby air coil. We are investigating the influence of magnet locations and polarities across frequencies using finite element simulation [

] and perceptual studies.

Wearable vibrotactile displays can stimulate the sense of touch and enrich diverse applications including gaming, computer-aided design, and remote surgery. However, when crafted from typical rigid robotic components, such interfaces tend to be heavy, bulky, and expensive. Sleeker designs may alleviate these disadvantages, but they often struggle to create clear haptic cues.

In this project we developed a lightweight wearable silicone ﬁnger sheath that can deliver salient and rich vibrotactile cues via electromagnetic actuation []. We fabricate the sheath on a ferromagnetic mandrel with a process based on dip molding. A miniature neodymium magnet embedded within the silicone layers is driven to vibrate by applying alternating current to a nearby air-coil. The bidirectional coupling between the magnet and the skin and the enlarged stimulation area created by the rubber sheath contribute to enhanced sensation on the fingertip.

Experiments were conducted to determine the amplitude of the magnetic force and the frequency response function for the displacement amplitude of the magnet perpendicular to the skin. In addition, high-ﬁdelity ﬁnite element analyses based on the DigiTip model [] were performed to simulate the dynamic response of the device covering the ﬁngertip to investigate the trends observed in the measurements. The experimental and simulated results showed consistent dynamic behavior from 10 to 1000 Hz, with the displacement amplitude decreasing after about 300 Hz. A cue identiﬁcation experiment and a demonstration in virtual reality validated the feasibility of this approach to fingertip haptics.

We are currently investigating the influence of magnet locations and polarities across frequencies using finite element simulations [] and human perception experiments with pairs of magnets embedded in silicone sheaths.

Members

Haptic Intelligence

Ifat Gertler

Postdoctoral Researcher

Haptic Intelligence

Giulia Ballardini

Research Scientist

Haptic Intelligence

Gokhan Serhat

Guest Scientist

Haptic Intelligence

Katherine J. Kuchenbecker

Director

Publications

Haptic Intelligence Robotics Miscellaneous Soft Magnetic Fingertip Devices for Clear Vibrotactile Feedback Gertler, I., Ballardini, G., Grüninger, F., Kuchenbecker, K. J. Hands-on demonstration presented at the IEEE World Haptics Conference (WHC), Suwon, South Korea, July 2025 (Published) BibTeX

Haptic Intelligence Article Fingertip Dynamic Response Simulated Across Excitation Points and Frequencies Serhat, G., Kuchenbecker, K. J. Biomechanics and Modeling in Mechanobiology, 23(4):1369-1376, August 2024 (Published)

Abstract ›

Predicting how the fingertip will mechanically respond to different stimuli can help explain human haptic perception and enable improvements to actuation approaches such as ultrasonic mid-air haptics. This study addresses this goal using high-fidelity 3D finite element analyses. We compute the deformation profiles and amplitudes caused by harmonic forces applied in the normal direction at four locations: the center of the finger pad, the side of the finger, the tip of the finger, and the oblique midpoint of these three sites. The excitation frequency is swept from 2.5 to 260 Hz. The simulated frequency response functions (FRFs) obtained for displacement demonstrate that the relative magnitudes of the deformations elicited by stimulating at each of these four locations greatly depends on whether only the excitation point or the entire finger is considered. The point force that induces the smallest local deformation can even cause the largest overall deformation at certain frequency intervals. Above 225 Hz, oblique excitation produces larger mean displacement amplitudes than the other three forces due to excitation of multiple modes involving diagonal deformation. These simulation results give novel insights into the combined influence of excitation location and frequency on the fingertip dynamic response, potentially facilitating the design of future vibration feedback devices.

DOI BibTeX

Haptic Intelligence Article Generating Clear Vibrotactile Cues with a Magnet Embedded in a Soft Finger Sheath Gertler, I., Serhat, G., Kuchenbecker, K. J. Soft Robotics, 10(3):624-635, June 2023 (Published)

Abstract ›

Haptic displays act on the user's body to stimulate the sense of touch and enrich applications from gaming and computer-aided design to rehabilitation and remote surgery. However, when crafted from typical rigid robotic components, they tend to be heavy, bulky, and expensive, while sleeker designs often struggle to create clear haptic cues. This article introduces a lightweight wearable silicone finger sheath that can deliver salient and rich vibrotactile cues using electromagnetic actuation. We fabricate the sheath on a ferromagnetic mandrel with a process based on dip molding, a robust fabrication method that is rarely used in soft robotics but is suitable for commercial production. A miniature rare-earth magnet embedded within the silicone layers at the center of the finger pad is driven to vibrate by the application of alternating current to a nearby air-coil. Experiments are conducted to determine the amplitude of the magnetic force and the frequency response function for the displacement amplitude of the magnet perpendicular to the skin. In addition, high-fidelity finite element analyses of the finger wearing the device are performed to investigate the trends observed in the measurements. The experimental and simulated results show consistent dynamic behavior from 10 to 1000 Hz, with the displacement decreasing after about 300 Hz. These results match the detection threshold profile obtained in a psychophysical study performed by 17 users, where more current was needed only at the highest frequency. A cue identification experiment and a demonstration in virtual reality validate the feasibility of this approach to fingertip haptics.

DOI BibTeX

Haptic Intelligence Article Free and Forced Vibration Modes of the Human Fingertip Serhat, G., Kuchenbecker, K. J. Applied Sciences, 11(12):5709, June 2021 (Published)

Abstract ›

Computational analysis of free and forced vibration responses provides crucial information on the dynamic characteristics of deformable bodies. Although such numerical techniques are prevalently used in many disciplines, they have been underutilized in the quest to understand the form and function of human fingers. We addressed this opportunity by building DigiTip, a detailed three-dimensional finite element model of a representative human fingertip that is based on prior anatomical and biomechanical studies. Using the developed model, we first performed modal analyses to determine the free vibration modes with associated frequencies up to about 250 Hz, the frequency at which humans are most sensitive to vibratory stimuli on the fingertip. The modal analysis results reveal that this typical human fingertip exhibits seven characteristic vibration patterns in the considered frequency range. Subsequently, we applied distributed harmonic forces at the fingerprint centroid in three principal directions to predict forced vibration responses through frequency-response analyses; these simulations demonstrate that certain vibration modes are excited significantly more efficiently than the others under the investigated conditions. The results illuminate the dynamic behavior of the human fingertip in haptic interactions involving oscillating stimuli, such as textures and vibratory alerts, and they show how the modal information can predict the forced vibration responses of the soft tissue.

DOI BibTeX