Data supporting the publication: Fingertip real contact area scales quadratically with input voltage in electrostatic actuation

Dataset of "Fingertip real contact area scales quadratically with input voltage in electrostatic actuation", which is accepted for Eurohaptics 2026.<br>Abstract:Touchscreens have become the dominant interface in consumer electronics, yet interactions with them remain primarily visual. Incorporating haptic feedback that simulates touch sensations could make these interactions more natural and intuitive. Electrostatic actuation, which modulates friction by attracting the finger toward a capacitive surface using an alternating voltage, offers a promising approach. The resulting increase in friction is often attributed to the rise in real contact area; however, direct experimental evidence linking voltage input parameters to real contact area and contact forces remains limited. Here, we use frustrated total internal reflection to directly image the real contact area while simultaneously measuring contact forces during controlled finger sliding under electrostatic actuation. We systematically vary voltage amplitude (75–150~V) and excitation frequency (30–230~Hz) and quantify the changes in contact area and forces as functions of these parameters. Our results reveal a quadratic dependence of real contact area, electrostatic attraction, and tangential force on voltage amplitude, with comparatively small effects of excitation frequency. These findings clarify the respective roles of voltage amplitude and frequency in the electrostatic modulation of finger contact mechanics, providing design guidelines for haptic display design.<br>The experiment consisted of five sessions, each conducted on a separate occasion. In each session, all combinations of four input voltage amplitudes (75, 100, 125, and 150 V) and five sine-wave frequencies (30, 80, 130, 180, and 230 Hz) were tested, with three repetitions per frequency-amplitude combination. Each trial consisted of a voltage-off phase followed by a voltage-on phase within the same sliding stroke. During each trial, the fingertip was moved laterally at a constant speed of 20 mm/s using the motorized stage, while the participant regulated the normal force to 1 N using real-time visual feedback. For each frequency-voltage combination, results were computed by averaging across the three repetitions within that session. <br>Details of the dataset can be found in the Readme file.

“静电驱动下指尖真实接触面积随输入电压呈二次方缩放”数据集，已被Eurohaptics 2026收录。
摘要：触控屏已成为消费电子领域的主流交互界面，但目前人机交互仍主要依赖视觉通路。引入可模拟真实触感的触觉反馈，能够让此类交互更加自然直观。静电驱动（electrostatic actuation）技术通过交变电压将指尖吸附至电容式表面以调节摩擦力，是一种极具潜力的解决方案。此前常将摩擦力的提升归因于真实接触面积的增大，但直接将电压输入参数与真实接触面积、接触力建立关联的实验证据仍较为匮乏。本研究利用受抑全内反射（frustrated total internal reflection）技术，在受控的指尖滑动过程中，直接成像获取真实接触面积的同时同步测量接触力。我们系统地改变电压幅值（75~150 V）与激励频率（30~230 Hz），并量化了接触面积与接触力随这两类参数的变化规律。研究结果表明，真实接触面积、静电吸引力与切向力（tangential force）均随电压幅值呈二次方依赖关系，而激励频率的影响相对较小。上述发现厘清了电压幅值与激励频率在指尖接触力学的静电调控中的各自作用，可为触觉显示器的设计提供指导准则。
本实验共包含5个测试批次，每个批次在独立时段完成。每个批次中，我们测试了4种输入电压幅值（75、100、125、150 V）与5种正弦波频率（30、80、130、180、230 Hz）的全部组合，每组频幅组合重复测试3次。每次测试包含一个电压关闭阶段与一个电压开启阶段，二者处于同一次滑动行程内。实验过程中，通过电动载物台（motorized stage）以20 mm/s的恒定速度横向移动指尖，受试者借助实时视觉反馈将法向力（normal force）维持在1 N。针对每组频压组合，我们通过该批次内的3次重复测试结果取平均以得到最终数据。
数据集的详细信息可参见Readme文件。