Haptic technology involves the use of electrical or mechanical means to stimulate afferent nerves or mechanoreceptors in the skin as the basis for creating sensations of physical touch that can ...qualitatively expand virtual or augmented reality experiences beyond those supported by visual and auditory cues alone. An emerging direction in this field involves the development of platforms that provide spatiotemporal patterns of sensation to the skin across not only the fingertips, but to any and all regions of the body, using thin, skin‐like technologies that impose negligible physical burden on the user. This review highlights the biological basis for skin interfaces of this type and the latest advances in haptics in the context of this ambitious goal, including electrotactile and vibrotactile devices that support perceptions of touch in form factors that have potential as skin‐integrated interfaces. The content includes a discussion of schemes for integrating these stimulators into programmable arrays, with an emphasis on scalable materials and designs that have the potential to support soft interfaces across large areas of the skin. A concluding section summarizes the potential consequences of successful research efforts in this area, along with key multidisciplinary challenges and associated research opportunities in materials science and engineering.
Haptic technologies qualitatively expand virtual reality experiences beyond visual and auditory cues to include perceptions of touch. This review highlights the latest advances in materials and devices designed to elicit such responses through vibratory excitations. A focus is on approaches that support large‐area engagements at any location across the body, beyond the fingertips and hands, as a thin, skin‐integrated interface.
A silk nanofiber‐networked bio‐triboelectric generator (Silk Bio‐TEG) is developed using an eco‐friendly and sustainable silk biomaterial with strong hydrogen bonding between peptide blocks. The ...electrospun Silk Bio‐TEG shows highly durable and reliable energy harvesting performances due to its notably high surface‐to‐volume ratio, mechanically super‐strong silk fibers, and fracture tolerant behavior of nanofiber‐networks.
Materials and fabrication approaches that allow integration of biodegradable/transient electronics onto diverse classes of biodegradable substrates are presented in this article. By first depositing, ...patterning, and etching the materials for the electronics and then integrating them on a substrate of interest, it is possible to use nearly any type of biodegradable material for this purpose. Component and system‐level studies of various devices and biodegradable polymers illustrate the capabilities and operational aspects. Dissolution studies and mechanics modeling results highlight different modes for transient behavior.
Dual-functioning displays, which can simultaneously transmit and receive information and energy through visible light, would enable enhanced user interfaces and device-to-device interactivity. We ...demonstrate that double heterojunctions designed into colloidal semiconductor nanorods allow both efficient photocurrent generation through a photovoltaic response and electroluminescence within a single device. These dual-functioning, all-solution-processed double-heterojunction nanorod light-responsive light-emitting diodes open feasible routes to a variety of advanced applications, from touchless interactive screens to energy harvesting and scavenging displays and massively parallel display-to-display data communication.
Here we demonstrate materials and operating conditions that allow for high-resolution printing of layers of quantum dots (QDs) with precise control over thickness and submicron lateral resolution and ...capabilities for use as active layers of QD light-emitting diodes (LEDs). The shapes and thicknesses of the QD patterns exhibit systematic dependence on the dimensions of the printing nozzle and the ink composition in ways that allow nearly arbitrary, systematic control when exploited in a fully automated printing tool. Homogeneous arrays of patterns of QDs serve as the basis for corresponding arrays of QD LEDs that exhibit excellent performance. Sequential printing of different types of QDs in a multilayer stack or in an interdigitated geometry provides strategies for continuous tuning of the effective, overall emission wavelengths of the resulting QD LEDs. This strategy is useful to efficient, additive use of QDs for wide ranging types of electronic and optoelectronic devices.
This paper proposes a model predictive control based on three voltage vectors for an interior permanent-magnet synchronous motor in a rotating reference frame. The proposed method can obtain the ...reference voltage vector quickly by predicting only one voltage vector during one sampling period using the characteristics of the deadbeat control. In addition, to obtain better steady-state performance, the optimal vector duration ratios can be obtained from the cost function to minimize the error between the predicted reference voltage vector and the synthesis vector by using the switching sequence relationship of a symmetrical three vector, which is different from applying a single voltage vector in the conventional finite-control-set model predictive control (FCS-MPC). To verify the proposed method, the experimental results are compared with the conventional FCS-MPC and two-vector-based MPC.
Summary
Globally, infection by seasonal influenza viruses causes 3–5 million cases of severe illness and 290,000–650,000 respiratory deaths each year. Various influenza vaccines, including ...inactivated split‐ and subunit‐type, recombinant and live attenuated vaccines, have been developed since the 1930s when it was discovered that influenza viruses could be cultivated in embryonated eggs. However, the protection rate offered by these vaccines is rather low, especially in very young children and the elderly. In this review, we describe the history of influenza vaccine development, the immune responses induced by the vaccines and the adjuvants applied. Further, we suggest future directions for improving the effectiveness of influenza vaccines in all age groups. This includes the development of an influenza vaccine that induces a balanced T helper cell type 1 and type 2 immune responses based on the understanding of the immune system, and the development of a broad‐spectrum influenza vaccine that can increase effectiveness despite antigen shifts and drifts, which are characteristics of the influenza virus. A brighter future can be envisaged if the development of an adjuvant that is safe and effective is realized.
Low modulus, compliant systems of sensors, circuits and radios designed to intimately interface with the soft tissues of the human body are of growing interest, due to their emerging applications in ...continuous, clinical-quality health monitors and advanced, bioelectronic therapeutics. Although recent research establishes various materials and mechanics concepts for such technologies, all existing approaches involve simple, two-dimensional (2D) layouts in the constituent micro-components and interconnects. Here we introduce concepts in three-dimensional (3D) architectures that bypass important engineering constraints and performance limitations set by traditional, 2D designs. Specifically, open-mesh, 3D interconnect networks of helical microcoils formed by deterministic compressive buckling establish the basis for systems that can offer exceptional low modulus, elastic mechanics, in compact geometries, with active components and sophisticated levels of functionality. Coupled mechanical and electrical design approaches enable layout optimization, assembly processes and encapsulation schemes to yield 3D configurations that satisfy requirements in demanding, complex systems, such as wireless, skin-compatible electronic sensors.
Diverse touch experiences offer a path toward greater human–machine interaction, which is essential for the development of haptic technology. Recent advances in triboelectricity‐based touch sensors ...provide great advantages in terms of cost, simplicity of design, and use of a broader range of materials. Since performance solely relies on the level of contact electrification between materials, triboelectricity‐based touch sensors cannot effectively be used to measure the extent of deformation of materials under a given mechanical force. Here, an ion‐doped gelatin hydrogel (IGH)‐based touch sensor is reported to identify not only contact with an object but also deformation under a certain level of force. Switchable ionic polarization of the gelatin hydrogel is found to be instrumental in allowing for different sensing mechanisms when it is contacted and deformed. The results show that ionic polarization relies on conductivity of the hydrogels. Quantitative studies using voltage sweeps demonstrate that higher ion mobility and shorter Debye length serve to improve the performance of the mechanical stimuli‐perceptible sensor. It is successfully demonstrated that this sensor offers dynamic deformation‐responsive signals that can be used to control the motion of a miniature car. This study broadens the potential applications for ionic hydrogel‐based sensors in a human–machine communication system.
The rationally designed ion‐doped gelatin hydrogels (IGHs) provide dynamic tactile perception under consecutive events of mechanical stimuli, benefiting from the combined characteristics of triboelectric and piezoionic effects. Through broader theoretical studies on ion dynamics, remarkable sensitivity in deformative circumstances is achieved. The developed dynamic tactile sensing‐based communicator enables simultaneous recognition of pressure and texture through in‐depth analyses of ion dynamics.
PDF
