Imperceptible electrooculography graphene sensor system for human-robot interface

Electrooculography (EOG) is a method to record the electrical potential between the cornea and the retina of human eyes. Despite many applications of EOG in both research and medical diagnosis for many decades, state-of-the-art EOG sensors are still bulky, stiff, and uncomfortable to wear. Since EOG has to be measured around the eye, a prominent area for appearance with delicate skin, mechanically and optically imperceptible EOG sensors are highly desirable. Here, we report an imperceptible EOG sensor system based on noninvasive graphene electronic tattoos (GET), which are ultrathin, ultrasoft, transparent, and breathable. The GET EOG sensors can be easily laminated around the eyes without using any adhesives and they impose no constraint on blinking or facial expressions. High-precision EOG with an angular resolution of 4 degrees of eye movement can be recorded by the GET EOG and eye movement can be accurately interpreted. Imperceptible GET EOG sensors have been successfully applied for human-robot interface (HRI). To demonstrate the functionality of GET EOG sensors for HRI, we connected GET EOG sensors to a wireless transmitter attached to the collar such that we can use eyeball movements to wirelessly control a quadcopter in real time

Three-dimensional, multifunctional neural interfaces for cortical spheroids and engineered assembloids.

Three-dimensional (3D), submillimeter-scale constructs of neural cells, known as cortical spheroids, are of rapidly growing importance in biological research because these systems reproduce complex features of the brain in vitro. Despite their great potential for studies of neurodevelopment and neurological disease modeling, 3D living objects cannot be studied easily using conventional approaches to neuromodulation, sensing, and manipulation. Here, we introduce classes of microfabricated 3D frameworks as compliant, multifunctional neural interfaces to spheroids and to assembloids. Electrical, optical, chemical, and thermal interfaces to cortical spheroids demonstrate some of the capabilities. Complex architectures and high-resolution features highlight the design versatility. Detailed studies of the spreading of coordinated bursting events across the surface of an isolated cortical spheroid and of the cascade of processes associated with formation and regrowth of bridging tissues across a pair of such spheroids represent two of the many opportunities in basic neuroscience research enabled by these platforms

Modular and reconfigurable wireless e-tattoo platform for mobile physiological sensing

Moving from traditional healthcare methods of monitoring biometrics to an individualized wearable modality promises to reduce healthcare expenses and to present better values to the end-user. Over the past few years, ultrathin and ultrasoft epidermal electronics (a.k.a. e-tattoos) have emerged as the next generation wearables. Considering health monitoring’s unlimited potential applications in telemedicine, performance tracking, human-machine interface (HMI), and personalized mobile health, it is paramount to develop more affordable, dependable, and unobstructive biometric monitoring methods compared to current expensive and confining systems. However, it is impossible to build an all-purpose e-tattoo that can accommodate such a wide range of applications, and e-tattoos are only practically useful when they can operate wirelessly. Thus, I report the design, fabrication, and validation of modular and reconfigurable wireless e-tattoos for personalized physiological sensing. Such modular e-tattoos are comprised of a multilayer stack of stretchable layers featuring distinct functionalities: a) a near field communication (NFC) layer capable of wireless power harvesting and data transmission, or battery charging, b) Bluetooth (BT) long-distance data transmission, c) functional circuit layers, d) a passive electrode/sensor layer. These layers can be disassembled and swapped out multiple times to form custom e-tattoos with user-specified sensing capabilities. To implement such flexible e-tattoos, I invent a “cut-solder-paste” microfabrication method which is rapid-prototyped via a dry, digital and cost-effective freeform manufacture process. The mechanical strain and strain-dependent characteristics of the stretchable antenna have been analyzed by finite element method (FEM). I also demonstrate reconfigurability of such modular e-tattoos so that they can be disassembled and reassembled multiple times. Multimodal e-tattoos are stretchable by up to 20% and capable of wirelessly measuring skin hydration, skin temperature, oxygen saturation level (SpO₂), heart rate, electrocardiogram (ECG), seismocardiogram (SCG) and body motion, also estimating continuous real-time blood pressure (BP). Moreover, I report a novel magnetic field repeater (feeding coil) on clothes by leveraging embroidery method and wireless capability. Utilizing this engineering framework, it enables not only more dependable and long-term but also continuous and real-time ambulatory monitoring of a variety of biometrics. I believe that this platform opens the door for accessible, and affordable personalized healthcare monitoring in the near future.Electrical and Computer Engineerin

Suction effects in cratered surfaces.

It has been shown experimentally that cratered surfaces may have better adhesion properties than flat ones. However, the suction effect produced by the craters, which may be chiefly responsible for the improved adhesion, has not been properly modelled. This paper combines experimental, numerical simulation and analytical approaches towards developing a framework for quantifying the suction effect produced by isolated craters and cratered surfaces. The modelling approach emphasizes the essential role of large elastic deformation, while the airflow dynamics, microscopic mechanisms, like surface tension and air permeation, and rate-dependence are neglected. This approach is validated using experimental data for isolated hemi-spherical craters. The modelling approach is further applied to spherical cap (not necessarily hemi-spherical) craters with the objective of identifying optimal geometric and material properties, as well as the minimum preload necessary for attaining the maximum suction force. It is determined that stiff polymers with deep craters are capable of producing large suction forces. For soft materials, central to biomedical applications, large suction forces can be attained by reinforcing deep craters with thin stiff layers. Parametric optimization studies of reinforced craters reveal that some of them perform beyond common expectations. However, those high-performance reinforced craters are prone to surface instabilities, and therefore the practical use of such craters may be problematic

Influence of lattice oxygen on the catalytic activity of blue titania supported Pt catalyst for CO oxidation

© The Royal Society of Chemistry 2021.Despite extensive research into understanding the reaction mechanism for CO oxidation over transition metals supported on TiO2, the active species for oxidation remains controversial. Herein, the characteristics of the active oxygen species of blue TiO2with a higher concentration of oxygen vacancies as a model catalyst with deposited nano-sized Pt toward CO oxidation are unraveled. Pt deposited on blue TiO2showed 8.8 times higher catalytic activity than that on TiO2at 200 °C. Formation of the oxygen vacancies induced electron generation, and the electrons were transferred to CO, weakening the binding strength. The ratio of lattice oxygen on the top surface of Pt/blue TiO2decreased from 50.4% before the reaction to 6.1% during the reaction, as analyzed by near ambient pressure X-ray photoelectron spectroscopy. The results directly show that the facile reducibility of surface lattice oxygen of blue TiO2leads to the high activity of CO oxidation.11Nsciescopu

Geographical discrimination of dried chili peppers using femtosecond laser ablation-inductively coupled plasma-mass spectrometry (fsLA-ICP-MS)

This study presents a method for discriminating the geographical origin of dried chili peppers using femtosecond laser ablation-inductively coupled plasma-mass spectrometry (fsLA-ICP-MS) and multivariate analysis, such as orthogonal partial least squares discriminant analysis (OPLS-DA), heatmap analysis, and canonical discriminant analysis (CDA). Herein, 102 samples were analyzed for the content of 33 elements using optimized conditions of 200 Hz (repetition rate), 50 μm (spot size), and 90% (energy). Significant differences in count per second (cps) values of the elements were observed between domestic and imported peppers, with variations of up to 5.66 times (133Cs). The OPLS-DA model accuracy achieved an R2 of 0.811 and a Q2 of 0.733 for distinguishing dried chili peppers of different geographical origins. The variable importance in projection (VIP) and s-plot identified elements 10 and 3 as key to the OPLS-DA model, and in the heatmap, six elements were estimated to be significant in discriminating between domestic and imported samples. Furthermore, CDA showed a high accuracy of 99.02%. This method can ensure food safety for consumers, and accurately determine the geographic origin of agricultural products

FEM loading-unloading cycle of hemi-spherical craters from Suction effects in cratered surfaces

Deformation configurations of specimens with the same crater shape but different stiffness

Reversible Switching Phenomenon in Diarylethene Molecular Devices with Reduced Graphene Oxide Electrodes on Flexible Substrates

Photoswitching molecular electronic devices with reduced graphene oxide (rGO) top electrodes on flexible substrates are fabricated and characterized. It has been reported previously that diarylethene molecular devices with poly-(3,4-ethylenedioxythiophene) stabilized with poly-(4-styrenesulfonic acid)/Au top electrodes can hold two stable electrical conductance states when the devices are exposed to UV or visible light during device fabrication. However, those devices fail to show the reversible switching phenomenon in response to illumination after device fabrication. By employing conducting and transparent rGO top electrodes, it is demonstrated that the diarylethene molecular devices show a reversible switching phenomenon, i.e., the fabricated devices change their conductance state in response to the alternating illumination with UV and visible light. Furthermore, the molecular devices with rGO top electrodes also exhibit good longtime stability and reliable electrical characteristics when subjected to various mechanical stresses (bending radius down to 5 mm and bending cycle over 104)

Reversible Switching Phenomenon in Diarylethene Molecular Devices with Reduced Graphene Oxide Electrodes on Flexible Substrates

Photoswitching molecular electronic devices with reduced graphene oxide (rGO) top electrodes on fl exible substrates are fabricated and characterized. It has been reported previously that diarylethene molecular devices with poly-(3,4-ethylenedioxythiophene) stabilized with poly-(4-styrenesulfonic acid)/Au top electrodes can hold two stable electrical conductance states when the devices are exposed to UV or visible light during device fabrication. However, those devices fail to show the reversible switching phenomenon in response to illumination after device fabrication. By employing conducting and transparent rGO top electrodes, it is demonstrated that the diarylethene molecular devices show a reversible switching phenomenon, i.e., the fabricated devices change their conductance state in response to the alternating illumination with UV and visible light. Furthermore, the molecular devices with rGO top electrodes also exhibit good longtime stability and reliable electrical characteristics when subjected to various mechanical stresses (bending radius down to 5 mm and bending cycle over 10 4 ).131311sciescopu