Skin preparation-free, stretchable microneedle adhesive patches for reliable electrophysiological sensing and exoskeleton robot control.

High-fidelity and comfortable recording of electrophysiological (EP) signals with on-the-fly setup is essential for health care and human-machine interfaces (HMIs). Microneedle electrodes allow direct access to the epidermis and eliminate time-consuming skin preparation. However, existing microneedle electrodes lack elasticity and reliability required for robust skin interfacing, thereby making long-term, high-quality EP sensing challenging during body movement. Here, we introduce a stretchable microneedle adhesive patch (SNAP) providing excellent skin penetrability and a robust electromechanical skin interface for prolonged and reliable EP monitoring under varying skin conditions. Results demonstrate that the SNAP can substantially reduce skin contact impedance under skin contamination and enhance wearing comfort during motion, outperforming gel and flexible microneedle electrodes. Our wireless SNAP demonstration for exoskeleton robot control shows its potential for highly reliable HMIs, even under time-dynamic skin conditions. We envision that the SNAP will open new opportunities for wearable EP sensing and its real-world applications in HMIs.

Design of a Flexible High-Density Surface Electromyography Sensor.

In recent years, high-density surface electromyography (HD-sEMG) has shown promising advantages in many robotics applications. Using HD-sEMG can not only reduce the sensitivity of the sensor position on the muscle belly but can also facilitate the acquisition of more muscle activity information due to spatial sampling. As current commercial HD-EMG systems use stationary amplifiers, leading to bulky measurements and poor portability, the interest in developing an HD-EMG sensor has increased. However, the insufficient electrode density and complicated fabrication process are challenges to overcome. In this paper, we propose a flexible HD-EMG sensor with an on-board amplifier capable of a density level of 0.53 channel/cm2, higher than those in previous works. First, we investigated the effects of different sensor parameters (i.e., the electrode material, the inter-electrode distance (IED) and the size of the electrode) on the measured signal quality. Second, a low-cost, easily fabricated, easily customized HD-EMG fabrication method was proposed based on the selected sensor parameters with a signal-to-noise ratio (SNR) comparable to those of commercial sensors. Finally, we applied a muscle activation estimation algorithm to validate the feasibility of the designed HD-EMG sensor, showing higher estimation accuracy levels. The results here demonstrate that the designed HD-EMG sensor can be used as an effective human-machine interface for robotics applications.

Virtual-reality Cataract Surgery Simulator Using Haptic Sensory Substitution in Continuous Circular Capsulorhexis.

Cataract is one of the most common geriatric diseases, and surgery is known to be the best treatment. Despite the increasing demand for cataract surgery, the opportunity for novice residents to practice cataract surgery is gradually diminishing as the patient and animal ethics become strict. Therefore, there have been many attempts to overcome the lack of experience by using virtual reality training system. So far, most of the surgical training simulation devices so far focused on visual training, and when they have a haptic sense, they are tethered to a fixed station, which is different from the feeling of moving the actual surgical tool. In this study, we have developed a haptic surgical training tool with sensory substitution and virtual-reality-based cataract surgery simulator. To assess and reproduce the tactile senses during surgery, we prepared viscoelastic lens dummies and measured vibrations in contact and motion required during Continuous Circular Capsulorhexis (CCC). Based on measurement we designed vibration models for haptic sensory substitution and applied them to virtual reality simulator. With complete virtual reality training system, the contact vibration was successfully implemented for virtual contacts to reproduced realistic haptic senses.