Human Palm Skin Research Articles

Power Generation from Moisture Fluctuations Using Polyvinyl Alcohol-Wrapped Dopamine/Polyvinylidene Difluoride Nanofibers.

Despite the boom in the water-triggered electric power generation technologies, few attempts have been made with a broader horizonyielding the electricity from sweat, which is of great value for low-power-consumption wearable electronics. Here, an electromechanical coupling and humidity-actuated two-in-one humidity actuator-driven piezoelectric generator (HAPG) are reported, that can yield continuous electric power from fluctuations in the ambient humidity. It is composed of polyvinyl alcohol (PVA)-wrapped highly aligned dopamine (DA)/polyvinylidene fluoride (PVDF) shell/core nanofibers (PVA@DA/PVDF NFs). As-received PVA@DA/PVDF NFs can exchange water with the ambient humidity to perform expansion and contraction and convert them into electric power. An all-fiber-based portable HAPG is fabricated and tested on human palm skin. The devices show high sensitivity and accuracy for converting the mental sweating-derived continuous moisture fluctuations into electric power. This electric power can be stored in capacitors, which is expected to power micro- and nano-electronic devices or be used in electrotherapy such as electrical stimulation to promote wound healing. Beyond this, the obtained voltage profiles exhibit unique features that can reflect the typical sweat damping oscillation curve features.

Human‐Palm‐Inspired Artificial Skin Material Enhances Operational Functionality of Hand Manipulation

AbstractHuman skin plays an important role in hand manipulation by making a stable grasp with an enlarging contact area while providing a firm hold on the object. However, satisfying these two functions is contradictory in conventional single‐layer artificial skin. Softer skin material would increase the contact area, which is advantageous in maintaining the stability, but it decreases the manipulability since the object tends to make uncontrollable movement within the softer skin, and vice versa for harder skin material. This paper presents a biomimetic three‐layer skin structure inspired by human palm skin and shows that both stability and manipulability can be enhanced with the three‐layer structure. To achieve the unique stiffness characteristics of the human palm skin, a porous latex structure, which is highly compressible but tough in tensile direction, is chosen as the subcutaneous fat layer. Through the novel experimental setup and the finite element method simulations, it is found that the porous latex structure is the key structure contributing to both stability and manipulability. Furthermore, it is demonstrated that a robotic hand with the proposed skin material shows enhanced robustness in grasping tasks. With the proposed skin material, the robotic hands would be more advantageous for challenging manipulation tasks.

Noninvasive blood glucose monitoring in the terahertz frequency range

Human skin optical properties were studied in vivo using terahertz (THz) time-domain spectroscopy. For the attenuated total internal reflection (ATR) the silicon Dowe prism was used. The measurements were carried out on six volunteers with normal blood glucose concentration and in good health. A standard oral glucose tolerance test was also performed. The ATR spectra of palm skin were consecutively measured at 0–90 min after glucose intake. The variations of the ATR spectra of human skin were correlated with the changes in blood glucose level. The amplitude of ATR signal of human palm skin increased and the phase decreased when glucose concentrations in blood rose above the normal level. Our results demonstrate the possibility of a non-invasive real-time measurement of blood glucose concentration.

Chemiluminescent imaging of transpired ethanol from the palm for evaluation of alcohol metabolism.

A 2-dimensional imaging system was constructed and applied in measurements of gaseous ethanol emissions from the human palm. This imaging system measures gaseous ethanol concentrations as intensities of chemiluminescence by luminol reaction induced by alcohol oxidase and luminol-hydrogen peroxide-horseradish peroxidase system. Conversions of ethanol distributions and concentrations to 2-dimensional chemiluminescence were conducted on an enzyme-immobilized mesh substrate in a dark box, which contained a luminol solution. In order to visualize ethanol emissions from human palm skin, we developed highly sensitive and selective imaging system for transpired gaseous ethanol at sub ppm-levels. Thus, a mixture of a high-purity luminol solution of luminol sodium salt HG solution instead of standard luminol solution and an enhancer of eosin Y solution was adapted to refine the chemiluminescent intensity of the imaging system, and improved the detection limit to 3 ppm gaseous ethanol. The highly sensitive imaging allows us to successfully visualize the emissions dynamics of transdermal gaseous ethanol. The intensity of each site on the palm shows the reflection of ethanol concentrations distributions corresponding to the amount of alcohol metabolized upon consumption. This imaging system is significant and useful for the assessment of ethanol measurement of the palmar skin.

High Speed Spectral Optical Coherence Tomography for Imaging Biological Tissue <i>In Vivo</i>

A high speed spectral optical coherence tomography (SOCT) system was demonstrated. An achievable scanning speed of 92k line/sec has been reached and it can acquire 3-dimensional data sets in ~3 second. The axial resolution of ~13μm and lateral resolution of ~16μm have been realized. The system is capable of a theoretical depth measurement 3.2mm in air. We also measured the sensitivity performance corresponding to difference depth and it demonstrated that our system can differentiate signal form noise at 3mm pathlength difference. Using the system, human palm skin was measured in vivo.