Heart failure is a major international health issue. Myocardial mass loss and lack of contractility are precursors to heart failure. Although, the treatment of cardiac injury is severely limited, cardiac tissue engineering is considered to be a promising approach [1]. In native heart tissue, the cardiac muscle cells are assembled in a conductive network, so the materials selected for cardiac tissue engineering should also be conductive. In the last decades, some conductive polymers(e.g., polythiophene (PT), polyaniline, polypyrrole, metals particles, carbontube (CNT), etc.) have been developed for the cardiac tissue engineering[2].However, these material are more or less defective, such as some of them are not conductive and soft enough. In this paper we make a kind of graphene foam with size controllable holes, primary rats myocardial cells are seeded in the foam. As we know, graphene is a good conductive material, and here we make it to a unique foam structure, so cells growth in a three-dimensional space (needn't worry about the material breaking when the cells are beating) and demonstrate higher cell attachment, spreading and tissue function.

The SEM images showed in Fig.1 are the structure of graphene foam, and primary rats myocardial cells are seeded in interior holes of the graphene foam. Fig.2 shows the cell state after they have been cultured in graphene foam for several days. Our study provides a method for preparing graphene material, which can be used to study myocardial tissue engineering in vitro.

Advantages of flexible polymer materials with developments in refined actuation and sensing can be intertwined for a promising platform to work on a resilient, adaptable manipulator aimed at a range of biomedical applications.  Moreover, soft magnetic material has an inherent property of high remanence like the permanent magnets [1-3] that can be further refined to meet ever-increasing demands in untethered and safe regulated medical environments. Although safe and favorable technology, due to the nonlinear relationship between electromagnetic torque and bending angle of the soft material, quantization of the magnetic field inside a deformable structure is still a nontrivial problem to investigate [4]. In this realm, we propose a novel soft-squishy, flexible force sensor approach for active tactile sensation that utilizes soft morphological computation. This research is motivated by hominoid finger’s extraordinary combination of fibroblast bone tissue and flexible muscle for grabbing and sensing effective force feedback while gripping a delicate, fragile object in real-time environment. We intend to create an electromagnetically driven tactile sensing system that will be an integration of actuation (magneto rheological paradigm and electromagnetic) and sensing elements (electrical conductivity). The main idea of this proposal will be to have a comparative study with electrical conductivity to address the value of stress generated by the human finger with close proximity. This device when actuated will change its morphology/stiffness and generate electrical stimulus transitions for different posture of embedded sensing. As a result, the proposed device can be proactive in sensing tasks depending upon the EM field variations. Conclusively, this work will be an example of soft morphological control in sensing, and projected to open a new trend in development of tactile sensing system for medical rehabilitation device and therein.

With the rapid development of MEMS (Micro-electro-mechanical Systems) fabrication technologies, manifolds microelectrodes with various structures and functions have been designed and fabricated for applications in biomedical research, diagnosis and treatment through electrical stimulation and electrophysiological signal recording. The flexible MEMS microelectrodes exhibit multi-aspect excellent characteristics, such as: lighter weight, smaller volume, better conforming to neural tissue and lower fabrication cost. In this talk, we mainly reviewed key technologies on flexible MEMS microelectrodes for neural interface in recent years, including: design and fabrication technology, flexible MEMS microelectrodes with fluidic channels and electrode-tissue interface modification technology for performance improvement. Furthermore, the future directions of flexible MEMS microelectrodes are discussed.

In this research, to meet the growing need of wearable electronic devices, a low cost and low energy consumption gas sensor array chip combined with printed electrodes and flexible substrate is developed. Eight different layouts are designed and the relation between sensitivity and electrode gap is discovered through the testing responses to different concentrations of ethanol and methane.

The flexible gas sensor integrated to wearable device can monitor those harmful volatile organic compounds and explosive gases real-time in our daily life and be part of the Internet of Things (IoT) . To achieve the ideal using condition and lower the price, resistive gas sensor array using polymer and carbon black mixture as sensing material may be the best choice due to the advantages of low cost, easy coating and room temperature operation.

The see-through three dimensional head-mounted display (3D-HMD) is designed by using the complex amplitude modulation technique. It can present true 3D images in real-time to the human eye to avoid the accommodation-vergence conflict of the conventional stereoscopic see-through displays. Optical experiments demonstrate that the designed 3D-HMD has continuous and wide depth cues with dynamic display ability.

Retinal prosthesis could electrically stimulate the survival retinal cells (ganglion, bipolar cells, etc.) to restore impaired vision function, which is expected to benefit people with visual degeneration due to inherited retinal degenerations like retinitis pigmentosa (RP) or age-related macular degeneration (AMD). To ensure effective stimulus and long-term implantation, some requirements of microelectrodes need to be satisfied stringently such as miniaturized geometry, reliability and good electrochemical performances.

Argus II (Second Sight, Sylmar, CA) as the world’s first commercial retinal prosthesis had only 60 channels and showed poor acuity [1]. From the simulation reported by James D. Weiland et al. [2], blind individuals became able to read newspaper, recognize faces and navigate in unfamiliar environments using 1000-channel flexible microelectrodes array (fMEA). More than 1000-channel fMEAs had also been investigated by Yu-Chong Tai et al. and Sangmin Lee et al. respectively [3][4]. In the paper, the fabrication, optimization and modification of 1025-channel fMEA are provided.

The schematic of fabrication of 1025-channel fMEA is shown in Fig.1. The 1025-channel fMEA contains two metal layers as the electrodes and metal trace and the polymer layer was used as insulation or substrate. In the micro-fabrication of the 1025-channel fMEA, Polyimide (PI) and parylene-C (PA) were chosen as the two substrate materials due to their excellent biocompatibility, flexibility and mechanical strength. The first and second metal layer was fabricated by the successive processes including photolithography (EVG 610, Austria) by using mask 1 and 2 respectively, deposition of titanium (Ti) and platinum (Pt) by using E-beam evaporation (SKY Technology Development, China) and lift off process. Each metal layer was covered with a deposed polymer as insulated layer. The pattern of each metal layer after lift off is given in Fig.2. After the formation of the final polymer layer, the sample was etched twice by oxygen reactive ion etching (RIE) using AZ4620 as hard mask to expose the electrodes for plating. One extra step was to electroplate the Pt gray on the exposed microelectrodes, as Pt gray electroplating would bring large surface which would reduce the impedance considerably and is desirable for retinal prosthesis [5].

Metal peeling phenomenon has happened during the fMEA fabrication, and it is indicated that Ti/Pt layer peeled from the polymer substrate through the energy dispersive spectrometer (EDS) analysis result. Pt and carbon atom percentages of two areas were 99.73% and 99.79% respectively as shown in Fig.3 (1). The results indicate the Ti/Pt metal layer peeled from the PI substrate. In order to enhance the adhesion between Ti/Pt layer and PI, O₂ plasma pre-treatment was presented to roughen the PI surface. Figure .3 (2) and (3) show the scanning electron microscope (SEM) and atomic force microscope (AFM) image of the surface of O₂ plasma-treated PI films with different RIE chamber pressure. Obviously, the treated PI surface showed irregular nano-scale hairs. The root-mean-squared (RMS) roughness of treated PI film was 34.7 nm, 22.8 nm, 18.9 nm and 15.2 nm respectively. A 10-channel fMEA was fabricated on untreated PI and pre-treated PI, shown in Fig.3 (4). It indicates plasma surface roughening treatment could enhance adhesion between metal layer and PI substrate.

A 24-channel fMEA was used to facilitate the investigation of the electrochemical properties for the 1025-channel fMEA.  The contact pads were wire-bonded to a printed circuit board (PCB) as shown in Fig.4 (1). The electroplated fMEA is shown in Fig.4 (2). Therefore, the impedance of microelectrodes or electroplate Pt-gray became measurable. The charge storage capacity (CSC) of the plated microelectrodes is calculated as 83.2 mC/cm² by integrating the areas under voltammograms from the CV curve as shown in Fig.5. The EIS presents a comparison of the impedance for the microelectrodes with and without Pt-gray as shown in Fig.6. The electrochemical impedance was significantly reduced from 110 kΩ to 16 kΩ at 1 kHz.

In conclusion, the 1025-channel fMEA was fabricated. O₂ plasma pre-treatment (RIE) is proved to be useful to enhance the adhesion between the metal layer and PI as it has roughened the PI surface. CSC of fMEA with Pt coated is found to be larger comparing with those without Pt-gray. The electrochemical impedance reduced to 16KΩ on samples coated with Pt-gray. The interface impedance reduced around one order of magnitude, which is promising for various high-density neural electrodes in rehabilitation medicine and brain sciences.

Real-time arterial pulse monitoring facilitates early detection of diseases and disorders of human heart and vascular system, and can improve patient survival rate and reduces healthcare costs. However, current pulse monitoring devices are cumbersome and fail to conform to the skin perfectly. In contrast, wearable devices can enable point-of-care health monitoring and provide advantages such as unobtrusiveness, compact size, and light weight. In this presentation, a soft microtubular sensor as small as a strand of hair is proposed as a fast, low cost, reliable and imperceptible human pulse monitoring solution. This microtubular sensor features a unique architecture comprising a liquid-state conductive element (eGaIn) core and an ultrathin silicone elastomer microtube, which responds to subtle epidermal pressure perturbations based on sensor resistance change. Its performance, such as sensitivity, durability and wearability, is investigated. The microtubular sensor can distinguish forces as small as 5 mN and possesses a high force sensitivity of 68 N^-1, and can withstand cyclical compressive loading. Brachial and radial arterial pulse waves are continuously monitored with high fidelity using the microtubular sensor. The microtubular sensor showed that, compared to the rest state, radial pulse rate and pressure after exercise increased by a factor of ~1.25 and ~1.5, respectively. The outcome of the proposed sensor demonstrates great potential in developing wearable devices for point of care health monitoring.

Water purification is the recent emergence in handling sewage and contaminated solution from different sources, such as industrial and domestic disposal. Such practice is being comprehensively explored to foresee whether it could be applicable in our lives since a couple of unpredicted toxic chemicals in wastewater may pose a significant risk to people. Environmentally-friendly research on water purification stands out as a promising solution, therefore, water purification by utilizing natural sunlight and nanomaterials was proposed by scientists. This thought incorporates raw environmental resource into chemical reaction of chosen materials. Literally, photocatalytic water purification is the decomposition of organic solution into less harmful products under the irradiation of sunlight. To quickly realize how photocatalytic reaction is proceeding in a compact and observable scale, a small-size of solar reactor could also be fostered because of its high surface to volume ratio. Consequently, Wang et al.¹ claimed that the technology is undergoing rapid development due to its tremendous potential in the fast testing field in environmental science. In the essay, the mechanism and its diverse application of light-induced water purification by using catalysts in micro-reactors will be discussed in an ordered manner.

Morphology and composition control of the perovskite thin films are of importance to develop high efficient perovskite solar cells. Previously, my group has demonstrated a 13% power conversion efficiency perovskite solar cells using two-step ultrasonic spray techniques. In this talk, I will present our attempts to optimize the perovskite thin film crystallinity and composition. Seed growth method is introduced to grow platelet nanostructured PbI2 thin film on organic transport layer PEDOT:PSS. The platelet PbI2 is discovered to be more effectively converted into perovskite films when subject to sprayed droplets of methylammonium, which enables a thicker perovskite to be formed with less unreacted PbI2, compared to those converted from compact PbI2 thin films. The influence of adding MABr in the PbI2 solution on the resulting solar cells will also be presented.

As is well known, energy crisis are becoming a worldwide problem and researchers are making every effort to search for the green and renewable energy source. To solve the problem, self-powered system has been proposed, which focuses on harvesting energy from the ambient environment. In 2012, utilizing the friction to generate energy based on the combination of triboelectric and electrostatic effect is presented as triboelectric nanogenerators (TENGs) which can be applied to biomedical and environmental systems as a power supply or a self-powered active sensor. 

In this talk, speaker will report their latest research work in TENGs with Hybrid mechanism. Frist, a r-shape hybrid piezoelectric and triboelectric NG is designed and integrated into a PC keyboard to harvest energy in the typing process, additionally, this device utilize in piano for self-recorder of composing. Second, another hybrid magnetic and triboelectric nanogenerators is introduced which can be used as self-powered visualized omnidirectional tilt sensing system. Third, an ultrathin flexible Piezoelectric and triboelectric Harvester for implantable applications will be discussed. The hybrid mechanism of Triboelectrical generator provides high performance and stability, which is important for powering implantable devices, touch panels, cell phone, artificial skins, sensor network nodes and so on.