No abstract

In this paper, a robotic applanation tonometry pulse sensor system has been developed to easily detect the pulse pressure index (PPI) using a pulse sensor array and reduce the position errors caused by manual operation when measuring the pulsation location of the subject's wrist using a robotic manipulator with automatic localization and pressurization. The amplitude change and shift of the pulse pressure (PP) caused by the unstable measurement angle of the tonometry device with a single sensor were measured and analyzed through an experiment with varying measurement angles. To evaluate the accuracy of the robotic tonometry system, the set PPI of the pulsatile simulator, which repeatedly generates artificial radial artery pulses, was compared with the PPI values estimated by the proposed methods. Accuracy evaluation of the pulse sensor indicates a coefficient of variability for the measured signals of up to 3.2 % and a minimum accuracy of 93.7 %; however, the PP calculated by a curve-fitting method applied to the measured signals from the array sensor was improved to an average of less than a 1.0 % coefficient of variability and 97.9 % accuracy. The developed robotic tonometry system represents a contribution to the radial pulse wave research field, which requires more accurate pulse wave analysis and PP measurements.

The primary goal of this study is to develop a mathematical model that can establish a transfer function relationship between the “external” pulse pressures measured by a tonometer and the “internal” pulse pressure in the artery. The purpose of the model is to accurately estimate and rebuild the internal pulse pressure waveforms using arterial tonometry measurements. To develop and validate a model without human subjects and operators for consistency, this study employs a radial pulse generation system, a robotic tonometry system, and a write model with an artificial skin and vessel. A transfer function model is developed using the results of the pulse testing and the mechanical characterization testing of the skin and vessel. To evaluate the model, the pulse waveforms are first reconstructed for various reference pulses using the model with tonometry data. They are then compared with pulse waveforms acquired by internal measurement (by the built-in pressure sensor in the vessel) the external measurement (the on-skin measurement by the robotic tonometry system). The results show that the model-produced pulse waveforms coinciding well with the internal pulse waveforms with small relative errors, indicating the effectiveness of the model in reproducing the actual pulse pressures inside the vessel.

Vibrotactile feedback in touch screen displays (TSDs) contributes to improved usability and enhanced engagement. It is prevalent in small consumer electronic devices, such as smart phones. While vibrotactile feedback is a desirable feature for large TSDs, it is limited in such devices due to a lack of proper actuators. In this study, we propose a thin vibrotactile actuator based on an electrostatic force mechanism suitable for mounting on the back of large TSDs. The primary goals of this study are to design and test a thin or slim electrostatic resonant actuator (ERA) and investigate its feasibility for large TSD applications. A prototype ERA was constructed by employing a “leaf” spring design to reduce the thickness and to support a mass that is grounded electrically. Upon applying a high-voltage input to the prototype, the electrostatic attraction force coupled with the spring’s restoring force makes the mass to oscillate, and the maximum vibration occurs at its resonant frequency. The ERA module testing shows that the prototype produced the maximum output acceleration of 2.5 g at its resonance frequency (99 Hz), which is significantly larger than the threshold value which humans can perceive. After validating that the thin ERA can produce sufficient vibrotactile sensations, a haptic touch display module consisting of a 17-inch touch panel supported by four ERAs was constructed. To experimentally evaluate the performance of this prototype, three distant input frequencies were used, and the acceleration response of the panel was measured at multiple points. The results show that the acceleration magnitude varies, exhibiting distinct patterns throughout the panel surface, when different input frequency values were applied. The results further show that the maximum acceleration magnitude is greater than that of the human-perceivable threshold values for the input frequencies considered in this study. Overall, the results show that the proposed ERA is feasible to use in large TSDs to convey vibration tactile sensations to users while keeping the thickness of the haptic interface module thin.

With the emergence of the metaverse and other human–computer interaction technologies, promising applications such as medical palpation training are growing for training and education purposes. Thus, the overarching goal of this study is to develop a portable and simple pulse pressure simulator that can reproduce age-specific pulse pressure waveforms for medical palpation training. For training applications, the simulator is required to produce accurate radial pulse waveforms consistently and repeatedly. To this end, exploiting the cam-based pneumatic pulse generation mechanism, this study intends to develop a cylindrical (or 3D) cam whose continually varying surface contains a wide range of age-related pulse pressure profiles. To evaluate the performance of the simulator, the reproduced pulse waveforms were compared with approximate radial pulse pressure waveforms based on in vivo data in terms of the augmentation index (AI) and L2 error. The results show that the errors were less than 10% for all ages, indicating that the proposed pulse simulator can reproduce the age-specific pulse waveforms equivalent to human radial pulse waveforms. The findings in this study suggest that the pulse simulator would be an excellent system for RAPP palpation training as it can reproduce a desired pulse accurately and consistently.