Process,Material,and Regulatory Considerations for 3D Printed Medical Devices and Tissue Constructs

Three-dimensional(3D)printing is a highly automated platform that facilitates material deposition in a layer-by-layer approach to fabricate pre-defined 3D complex structures on demand.It is a highly promising technique for the fabrication of personalized medical devices or even patient-specific tissue constructs.Each type of 3D printing technique has its unique advantages and limitations,and the selection of a suitable 3D printing technique is highly dependent on its intended application.In this review paper,we present and highlight some of the critical processes(printing parameters,build orientation,build location,and support structures),material(batch-to-batch consistency,recycling,protein adsorption,biocompatibility,and degradation properties),and regulatory considerations(sterility and mechanical properties)for 3D printing of personalized medical devices.The goal of this review paper is to provide the readers with a good understanding of the various key considerations(process,material,and regulatory)in 3D printing,which are critical for the fabrication of improved patient-specific 3D printed medical devices and tissue constructs.

Light-based 3D printing of stimulus-responsive hydrogels forminiature devices:recent progress and perspective

Miniature devices comprising stimulus-responsive hydrogels with high environmental adaptability are now considered competitive candidates in the fields of biomedicine,precise sensors,and tunable optics.Reliable and advanced fabricationmethods are critical formaximizing the application capabilities ofminiature devices.Light-based three-dimensional(3D)printing technology offers the advantages of a wide range of applicable materials,high processing accuracy,and strong 3D fabrication capability,which is suitable for the development of miniature devices with various functions.This paper summarizes and highlights the recent advances in light-based 3D-printed miniaturized devices,with a focus on the latest breakthroughs in lightbased fabrication technologies,smart stimulus-responsive hydrogels,and tunable miniature devices for the fields of miniature cargo manipulation,targeted drug and cell delivery,active scaffolds,environmental sensing,and optical imaging.Finally,the challenges in the transition of tunable miniaturized devices from the laboratory to practical engineering applications are presented.Future opportunities that will promote the development of tunable microdevices are elaborated,contributing to their improved understanding of these miniature devices and further realizing their practical applications in various fields.

Device Discovery in D2D Communication: Scenarios and Challenges

Device to Device (D2D) communication is expected to be anessential part of 5G cellular networks. D2D communication enables closeproximitydevices to establish a direct communication session. D2D communicationoffers many advantages, such as reduced latency, high data rates,range extension, and cellular offloading. The first step to establishing a D2Dsession is device discovery;an efficient device discovery will lead to efficientD2D communication. D2D device further needs to manage its mode of communication,perform resource allocation, manage its interference and mostimportantly control its power to improve the battery life of the device. Thiswork has developed six distinct scenarios in which D2D communication canbe initiated, considering their merits, demerits, limitations, and optimizationparameters. D2D communication procedures for the considered scenarioshave been formulated, based upon the signal flow, containing device discovery,resource allocation, and session teardown. Finally, latency for each scenariohas been evaluated, based on propagation and processing delays.

3D printing of high-precision and ferromagnetic functional devices

The development of projection-based stereolithography additive manufacturing techniques and magnetic photosensitive resins has provided a powerful approach to fabricate miniaturized magnetic functional devices with complex three-dimensional spatial structures.However,the present magnetic photosensitive resins face great challenges in the trade-off between high ferromagnetism and excellent printing quality.To address these challenges,we develop a novel NdFeB-Fe_(3)O_(4) magnetic photosensitive resin comprising 20 wt.%solid loading of magnetic particles,which can be used to fabricate high-precision and ferromagnetic functional devices via micro-continuous liquid interface production process.This resin combining ferromagnetic NdFeB microparticles and strongly absorbing Fe_(3)O_(4) nanoparticles is able to provide ferromagnetic capabilities and excellent printing quality simultaneously compared to both existing soft and hard magnetic photosensitive resins.The established penetration depth model reveals the effect of particle size,solid loading,and absorbance on the curing characteristics of magnetic photosensitive resin.A high-precision forming and ferromagnetic capability of the NdFeB-Fe_(3)O_(4) magnetic photosensitive resin are comprehensively demonstrated.It is found that the photosensitive resin(NdFeB:Fe_(3)O_(4)=1:1)can print samples with sub-40μm fine features,reduced by 87%compared to existing hard magnetic photosensitive resin,and exhibits significantly enhanced coercivity and remanence in comparison with existing soft magnetic photosensitive resins,showing by an increase of 24 times and 6 times,respectively.The reported NdFeB-Fe_(3)O_(4) magnetic photosensitive resin is anticipated to provide a new functional material for the design and manufacture of next-generation micro-robotics,electromagnetic sensor,and magneto-thermal devices.

Recent Progress in the Fabrication, Properties, and Devices of Heterostructures Based on 2D Materials

With a large number of researches being conducted on two?dimen?sional(2D) materials, their unique properties in optics, electrics, mechanics, and magnetics have attracted increasing attention. Accordingly, the idea of combining distinct functional 2D materials into heterostructures naturally emerged that pro?vides unprecedented platforms for exploring new physics that are not accessible in a single 2D material or 3D heterostructures. Along with the rapid development of controllable, scalable, and programmed synthesis techniques of high?quality 2D heterostructures, various heterostructure devices with extraordinary performance have been designed and fabricated, including tunneling transistors, photodetectors, and spintronic devices. In this review, we present a summary of the latest progresses in fabrications, properties, and applications of di erent types of 2D heterostruc?tures, followed by the discussions on present challenges and perspectives of further investigations.

Light–matter interaction of 2D materials:Physics and device applications

In the last decade, the rise of two-dimensional （2D） materials has attracted a tremendous amount of interest for the entire field of photonics and opto-electronics. The mechanism of light-matter interaction in 2D materials challenges the knowledge of materials physics, which drives the rapid development of materials synthesis and device applications. 2D materials coupled with plasmonic effects show impressive optical characteristics, involving efficient charge transfer, plas- monic hot electrons doping, enhanced light-emitting, and ultrasensitive photodetection. Here, we briefly review the recent remarkable progress of 2D materials, mainly on graphene and transition metal dichalcogenides, focusing on their tunable optical properties and improved opto-electronic devices with plasmonic effects. The mechanism of plasmon enhanced light-matter interaction in 2D materials is elaborated in detail, and the state-of-the-art of device applications is compre- hensively described. In the future, the field of 2D materials holds great promise as an important platform for materials science and opto-electronic engineering, enabling an emerging interdisciplinary research field spanning from clean energy to information technology.

High Performance 70nm CMOS Devices

A high performance 70nm CMOS device has been demonstrated for the first time in the continent, China. Some innovations in techniques are applied to restrain the short channel effect and improve the driving ability, such as 3nm nitrided oxide, dual poly Si gate electrode, novel super steep retrograde channel doping by heavy ion implantation, ultra shallow S/D extension formed by Ge PAI(Pre Amorphism Implantation) plus LEI(Low Energy Implantation), thin and low resistance Ti SALICIDE by Ge PAI and special cleaning, etc. The shortest channel length of the CMOS device is 70nm. The threshold voltages, G m and off current are 0 28V,490mS·mm -1 and 0 08nA/μm for NMOS and -0 3V,340mS·mm -1 and 0 2nA/μm for PMOS, respectively. Delays of 23 5ps/stage at 1 5V, 17 5ps/stage at 2 0V and 12 5ps/stage at 3V are achieved in the 57 stage unloaded 100nm CMOS ring oscillator circuits.

Feedback-based unequal error protection fountain code over device-to-device broadcast

To enhance encoding efficiency, an unequal error protection （UEP） broadcast scheme based on one additional feedback is proposed. Different from the equal probability selection for source packets in traditional fountain encoding, the proposed scheme calculates the packet loss ratio （PLR） according to the feedback results in systematic broadcast phase （SBP） and then optimizes the selection probability for source packets to guarantee higher level error protection for those source packets with larger PLRs. Thus the amount of unnecessarily redundant encoded packets during encoding broadcast phase （EBP） is decreased significantly. Numerical results show that the proposed scheme can recover 60% more packets than the traditional non-feedback broadcast scheme at the ex- pense of tolerably only one feedback procedure.

Balancing the customization and standardization:exploration and layout surrounding the regulation of the growing field of 3D-printed medical devices in China

Medical devices are instruments and other tools that act on the human body to aid clinical diagnosis and disease treatment,playing an indispensable role in modern medicine.Nowadays,the increasing demand for personalized medical devices poses a significant challenge to traditional manufacturing methods.The emerging manufacturing technology of three-dimensional(3D)printing as an alternative has shown exciting applications in the medical field and is an ideal method for manufacturing such personalized medical devices with complex structures.However,the application of this new technology has also brought new risks to medical devices,making 3D-printed devices face severe challenges due to insufficient regulation and the lack of standards to provide guidance to the industry.This review aims to summarize the current regulatory landscape and existing research on the standardization of 3D-printed medical devices in China,and provide ideas to address these challenges.We focus on the aspects concerned by the regulatory authorities in 3D-printed medical devices,highlighting the quality system of such devices,and discuss the guidelines that manufacturers should follow,as well as the current limitations and the feasible path of regulation and standardization work based on this perspective.The key points of the whole process quality control,performance evaluation methods and the concept of whole life cycle management of 3D-printed medical devices are emphasized.Furthermore,the significance of regulation and standardization is pointed out.Finally,aspects worthy of attention and future perspectives in this field are discussed.

A focus review on 3D printing of wearable energy storage devices

Three-dimensional(3D)printing has gained popularity in a variety of applications,particularly in the manufacture of wearable devices.Aided by the large degree of freedom in customizable fabrication,3D printing can cater towards the practical requirements of wearable devices in terms of light weight and flexibility.In particular,this focus review aims to cover the important aspect of wearable energy storage devices(WESDs),which is an essential component of most wearable devices.Herein,the topics discussed are the fundamentals of 3D printing inks used,the optimizing strategies in improving the mechanical and electrochemical properties of wearable devices and the recent developments and challenges of wearable electrochemical systems such as batteries and supercapacitors.It can be expected that,with the development of 3D printing technology,realization of the full potential of WESDs and seamless integration into smart devices also needs further in-depth investigations.

3D Printing of Next-generation Electrochemical Energy Storage Devices: from Multiscale to Multimaterial

The increasing energy requirements to power the modern world has driven active research into more advanced electrochemical energy storage devices(EESD)with both high energy densities and power densities.Wide range of newly discovered materials with promising electrochemical properties has shown great potential for next-generation devices,but their performance is normally associated with contradicting demands of thin electrodes and high mass loading that can be hardly achieved for practical applications.Design of three-dimensional(3D)porous electrodes can increase the mass loading while maintaining the effective charge transport even with thick electrodes,which has proven to be efficient to overcome the limitations.3D structures have also been demonstrated excellent structural stability to withstand strong strains and stresses generated during charge/discharge cycle.3D printing,which can fabricate various delicate and complex structural designs,thus offering brand-new opportunities for the rational design and facile construction of next-generation EESDs.The recent developments in 3D printing of next-generation EESDs with high performance are reviewed.Advanced/multiscale electrode structures,such as hierarchically porous structure that can be constructed via high-resolution 3D printing or with post-treatment,are further emphasized.The ability of current 3D printing techniques to fulfill multimaterial printing to fulfill simple packaging will be covered.

Determination of inhibitory activity of Salvia miltiorrhiza extracts on xanthine oxidase with a paper-based analytical device

A novel paper-based analytical device(PAD)was prepared and applied to determine the xanthine oxidase(XOD)inhibitory activity of Salvia miltiorrhiza extracts(SME).First,polycaprolactone was 3D printed on filter paper and heated to form hydrophobic barriers.Then the modified paper was cut according to the specific design.Necessary reagents including XOD for the colorimetric assay were immobilized on two separate pieces of paper.By simply adding phosphate buffer,the reaction was performed on the double-layer PAD.Quantitative results were obtained by analyzing the color intensity with the specialized device system(consisting of a smartphone,a detection box and sandwich plates).The 3Dprinted detection box was small,with a size of 9.0 cm×7.0 cm×11.5 cm.Color component G performed well in terms of linearity and detection limits and thus was identified as the index.The reaction conditions were optimized using a definitive screening design.Moreover,a 10%glycerol solution was found to be a suitable stabilizer.When the stabilizer was added,the activity of XOD could be maintained for at least 15 days under 4℃ or-20℃ storage conditions.The inhibitory activity of SME was investigated and compared to that of allopurinol.The results obtained with the PAD showed agreement with those obtained with the microplate method.In conclusion,the proposed PAD method is simple,accurate and has a potential for point-of-care testing.It also holds promise for use in rapid quality testing of medicinal herbs,intermediate products,and preparations of traditional Chinese medicines.

An improved 3D shape haptic rendering algorithm for finger mounted vibrotactile device

To improve the sense of reality on perception, an improved algorithm of 3D shape haptic rendering is put forward based on a finger mounted vibrotactile device. The principle is that the interactive information and the shape information are conveyed to users when they touch virtual objects at mobile terminals by attaching the vibrotactile feedback on a fingertip. The extraction of shape characteristics, the interactive information and the mapping of shape in formation of vibration stimulation are key parts of the proposed algorithm to realize the real tactile rendering. The contact status of the interaction process, the height information and local gradient of the touch point are regarded as shape information and used to control the vibration intension, rhythm and distribution of the vibrators. With different contact status and shape information, the vibration pattern can be adjusted in time to imitate the outlines of virtual objects. Finally, the effectiveness of the algorithm is verified by shape perception experiments. The results show that the improved algorithm is effective for 3D shape haptic rendering.

高通公司Device to Device技术国内专利布局现状研究

本文对高通公司在4G演进技术--移动终端设备间直接通信技术(D2D技术)国内专利申请概况进行了研究,对其在D2D技术领域的专利布局情况进行了分类和统计,初步分析和阐述了高通公司在该领域的专利积累情况。根据其近年的专利技术方案,概要性地整理了其技术发展路线,为我国国内企业在该领域的研究和标准化策略提供参考。

3D kinematicmandiblemodel to designmandibular advancement devices for the treatment of obstructive sleep apnea

Mandibular advancement devices(MADs)are one of the treatments used for Obstructive sleep apnea(OSA).MADs try to maintain the mandible in an advanced position to keep the upper airways open when sleeping.To achieve this goal,most current MADs limit the mouth opening to a few millimetres.The study of the kinematic behaviour of the patient’s jaw is essential in order to design devices that allow greater aperture ranges.For this purpose,a 3D multibody model that reproduces jaw movement has been developed in this work.To this end,the movement of the lower incisor has been determined by means of a vision system and reflective markers.In addition,the kinematics of the temporomandibular joint has been modelled.Next,the device is designed and printed using a cam-follower mechanism.This way,the cam profiles and the followers are optimally designed and positioned for each patient depending on the physiognomy of the jaw and the opening and advancing movement prescribed by the specialist.

Interference Suppression for MIMO Device to Device Pairs Underlaying Cellular Network

Device to device(D2D) communications may generate interference to the existing cellular networks.An interference suppression(IS) scheme is proposed in this paper.With this scheme,the threshold of D2D-pairs(D2D-Ps) communication was designed to reject the D2D-Ps which were not satisfied the threshold constraint,ensuring that the cellular users(CUs) had priority to use the spectrum resources.Then the interference from D2D-Ps at the receiver of CUs was eliminated first by precoding at the D2D transmitter and decoding at the CU's receiver.Next,the interference between D2D-Ps was suppressed by using interference alignment(IA).Performance analysis shows that the priority of CUs using the spectrum resources has been guaranteed;the interference generated on the cellular links is well eliminated;the interference between D2D-Ps can also be suppressed.

Can We Predict Menorrhagia with Intrauterine Contraceptive Device (IUCD) Insertion?

Objective: Studying sub endometrial vascularity and blood flow in cases using intrauterine contraceptive devices for contraception with and without menorrhagia compared to cases not using intrauterine contraceptive devices. Methods: Three hundred and fifteen women attending gynecology and family planning outpatient clinics in the maternity hospital, Ain Shams University were included in the study. They were classified into three groups, 105 women using IUCD with menorrhagia (group I), 105 women using IUCD without menorrhagia (group II), and 105 normal controls not using IUCD (group III). After excluding local causes for bleeding, blood disease or any medical disorders, transvaginal ultrasound including three dimensional power Doppler (3DPD) ultrasound was done for all women. Right and left uterine artery pulsatility index (PI) and resistance index (RI) were calculated, subednometrial blood flow RI and PI were obtained then 3DPD Vascular indices (VI, FI and VFI) of subendometrial blood flow were obtained for all cases. Statistical analysis was done to compare between the three groups. Results: A significant statistical difference was found as regards subendometrial vascularity indices, while there was no difference as regards bilateral uterine arteries Doppler indices in the three groups. Conclusion: Subendometrial vascularity in cases of menorrhagia with IUCD was markedly higher than in cases without menorrhagia and cases with no IUCD. 3DPD may be used for selection of cases prior to insertion of IUCD.

Development of Flexible Spherical Actuator with 3D Coordinate Measuring Device

Rehabilitation devices help to recover the physical abilities of patients. This study aims to develop a portable rehabilitation device that is safe to use when?patients are holding it by hands. In a previous study, to realize a home rehabilitation device, a flexible spherical actuator that can provide motion to patients was developed. In this study, to measure the relative position between both handling stages, a 3D coordinate measuring device using three wire-type linear potentiometers and an embedded controller was proposed and tested. In this paper, the spherical actuator with built-in 3D coordinate measuring device is described. The measuring method and experimental results obtained are also presented. The tracking position control of the actuator using the measuring device was carried out. As a result, the position of the handling stages can be successfully controlled using the feedback signal from the tested?measuring device.

An Analysis on Position Estimation, Drifting and Accumulated Error Accuracy during 3D Tracking in Electronic Handheld Devices

This work focuses on a brief discussion of new concepts of using smartphone sensors for 3D painting in virtual or augmented reality. Motivation of this research comes from the idea of using different types of sensors which exist in our smartphones such as accelerometer, gyroscope, magnetometer etc. to track the position for painting in virtual reality, like Google Tilt Brush, but cost effectively. Research studies till date on estimating position and localization and tracking have been thoroughly reviewed to find the appropriate algorithm which will provide accurate result with minimum drift error. Sensor fusion, Inertial Measurement Unit (IMU), MEMS inertial sensor, Kalman filter based global translational localization systems are studied. It is observed, prevailing approaches consist issues such as stability, random bias drift, noisy acceleration output, position estimation error, robustness or accuracy, cost effectiveness etc. Moreover, issues with motions that do not follow laws of physics, bandwidth, restrictive nature of assumptions, scale optimization for large space are noticed as well. Advantages of such smartphone sensor based position estimation approaches include, less memory demand, very fast operation, making them well suited for real time problems and embedded systems. Being independent of the size of the system, they can work effectively for high dimensional systems as well. Through study of these approaches it is observed, extended Kalman filter gives the highest accuracy with reduced requirement of excess hardware during tracking. It renders better and faster result when used in accelerometer sensor. With the aid of various software, error accuracy can be increased further as well.