Zhuangjian Liu

Institute Of High Performance Computing

Humans rely increasingly on sensors to address grand challenges and to improve quality of life in the era of digitalization and big data. For ubiquitous sensing, flexible sensors are developed to overcome the limitations of conventional rigid counterparts. Despite rapid advancement in bench-side research over the last decade, the market adoption of...

Soft robots have received much attention due to their impressive capabilities including high flexibility and inherent safety features for humans or unstructured environments compared with hard-bodied robots. Soft actuators are the crucial components of soft robotic systems. Soft robots require dexterous soft actuators to provide the desired deforma...

Recently, stretchable micro‐supercapacitors (MSCs) that can be easily integrated into electronic devices have attracted research and industrial attentions. In this work, three‐dimensional (3D) stretchable MSCs with an octet‐truss electrode (OTE) design have been demonstrated by a rapid digital light processing (DLP) process. The 3D‐printed electrod...

This paper contributes to a new design of the three-dimensional printable robotic ball joints capable of creating the controllable stiffness linkage between two robot links through pneumatic actuation. The variable stiffness ball joint consists of a soft pneumatic elastomer actuator, a support platform, an inner ball and a socket. The ball joint st...

Taking advantage of the powerful design potentials of isogeometric analysis, an integrated shape and size optimization framework for designing tetra chiral and anti-chiral auxetics is proposed to be capable of obtaining excellent designs without complicated implementation efforts. The framework utilizes a non-uniform rational basis spline (NURBS) b...

In the soft gripper design work, most of the designs such as gripping width and the design of finger actuator are purely based on experience, and repeated trial-and-error. In most scenarios, the designed actuators cannot achieve the best/optimized grasping performance with a specific design type. This optimized design is important especially for th...

Memristors constitute a promising functional component for information storage and in‐memory computing in flexible and stretchable electronics including wearable devices, prosthetics and soft robotics. Despite tremendous efforts made to adapt conventional rigid memristors to flexible and stretchable scenarios, stretchable and mechanical damage endu...

This article presents a versatile soft robotic gripper system whereby its fingers can be reconfigured into different poses such as scoop, pinch, and claw. This allows the gripper to efficiently and safely handle food samples of different shapes, sizes and stiffness such as uncooked tofu and broccoli floret. The 3D-printed fingers were tested to las...

Electronic skins equip robots and biomedical devices with intuitive skin‐like sensitivity. Performance‐driven design of electronic skins is a critical need for electronic or biomedical applications. Prior research primarily focuses on investigating effects of microstructures on sensor performance at low pressure ranges. However, having predictive a...

Stretchable electronics have advanced rapidly and many applications require high repeatability and robustness under various mechanical deformations. It has been described here that how a highly stretchable and reliable conductor composite made from helical copper wires and a soft elastomer, named eHelix, can provide mechanically robust and strain-i...

Significance We show a near–hysteresis-free piezoresistive sensor system from soft materials by using a method of generating unique three-dimensional nanoscale crack morphologies on metal-coated elastomeric microstructures. Our method addresses the major challenge of inherent electromechanical hysteresis faced by many electronic sensor skins using...

The surface functionality of biomaterial plays a primary role in determining its application in biorecognition and drug delivery. In our work, three types of synthetic tailoring polymer nanospheres with hierarchical architecture were constructed to obtain functional polymer layer with disparate chemical motifs for protein adsorption via surface imp...

The elastic conductor is crucial in wearable electronics and soft robotics. The ideal intrinsic elastic bulk conductors show uniform three-dimensional conductive networks and stable resistance during large stretch. A challenge is that the variation of resistance is high under deformation due to disconnection of conductive pathway for bulk elastic c...

A porous structure based on a solution-based approach is highly desired for electrodes in flexible electronics due to the requirements of efficient electron and mass transfer. However, such a structure is largely unexplored for MXene-based electrodes. Here, we developed a solution-based self-assembly system to produce a conductive film with a high...

Wearable epidermal sensors are of great importance to the next generation personalized healthcare. The adhesion between the flexible sensor and skin surface is critical for obtaining accurate, reliable and stable signals. Herein we present a facile approach to fabricate a micro-structured, natural silk fibroin protein based adhesive for achieving h...

Spider silks show unique combinations of strength, toughness, extensibility, and energy absorption. To date, it has been difficult to obtain spider silk-like mechanical properties using non-protein approaches. Here, we report on an artificial spider silk produced by the water-evaporation-induced self-assembly of hydrogel fibre made from polyacrylic...

Smart textiles that sense, interact, and adapt to environmental stimuli have provided exciting new opportunities for a variety of applications. However, current advances have largely remained at the research stage due to the high cost, complexity of manufacturing, and uncomfortableness of environment‐sensitive materials. In contrast, natural textil...

Sensitive sensing Neonatal care, particularly for premature babies, is complicated by the infants' fragility and by the need for a large number of tethered sensors to be attached to their tiny bodies. Chung et al. developed a pair of sensors that only require water to adhere to the skin and allow for untethered monitoring of key vital signs (see th...

Stretchable conductors are critical building blocks for enabling new forms of wearable and curvilinear electronics. In this paper, we introduce a new method using the interfacial design to enable stretchable conductors with ultra-high conductivity and robustness to strain using three-dimensional helical copper micro-interconnects embedded in an ela...

Four-Dimensional (4D) printing that enables 3D printed structures to change configurations over time has gained great attention due to its exciting potential in various applications. Among all the 4D printing materials, shape memory polymers (SMPs) possess higher stiffness, faster response rate, and therefore are considered as one of most promising...

Vitrimers are a new class of thermosetting polymers that can be thermally processed through bond exchange reactions (BERs) without losing network integrity. In engineering applications, the tunability of their thermomechanical properties is highly desirable to meet the requirements of different working conditions. Here, we report a simple composite...

Zeolites have many applications in the petrochemical and fine chemical industry and their functionalization does expand the spectrum of potentials. However, the integration of functional nanocrystals into zeolite frameworks with controlled size, dispersion, and crystallization behavior still remains a significant challenge. Here, a new synthesis of...

Soft and stretchable electronic devices are important in wearable and implantable applications because of the high skin conformability. Due to the natural biocompatibility and biodegradability, silk protein is one of the ideal platforms for wearable electronic devices. However, the realization of skin‐conformable electronic devices based on silk ha...

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 mecha...

In situ graphene hybridization is applied within the nanotube voids to reinforce carbon nanotube (CNT) networks, as demonstrated by X. M. Li, H. W. Zhu, Y. Fang, and co-workers on page 2078. The CNT–graphene hybrids effectively resist buckling deformation of the CNT network and load transfer within the hybridized films, which could be applied in we...

Transparent, stretchable films of carbon nanotubes (CNTs) have attracted significant attention for applications in flexible electronics, while the lack of structural strength in CNT networks leads to deformation and failure under high mechanical load. In this work, enhancement of the strength and load transfer capabilities of CNT networks by chemic...

Recently developed concepts for 3D, organ-mounted electronics for cardiac applications require an universal and easy-to-use mechanical model to calculate the average pressure associated with operation of the device, which is crucial for evaluation of design efficacy and optimization. A simple, accurate, easy-to-use, and universal model to quantify...

Recently developed concepts for 3D, organ mounted electronics for cardiac applications require a universal and easy-to-use mechanical model to calculate the average pressure associated with operation of the device, which is crucial for evaluation of design efficacy and optimization. This work proposes a simple, accurate, easy-to-use, and universal...

Many procedures in modern clinical medicine rely on the use of electronic implants in treating conditions that range from acute coronary events to traumatic injury. However, standard permanent electronic hardware acts as a nidus for infection: bacteria form biofilms along percutaneous wires, or seed haematogenously, with the potential to migrate wi...

The balloon-based catheters are attractive for the minimally invasive procedures because these catheters can be configured to match requirements on size and shape for the interaction with the soft tissue. An analytical mechanic model is developed for the deformed balloon to determine the shape of the inflated catheter. The bridges along latitudinal...

Magnetic resonance imaging (MRI) targeted and transrectal ultrasound (TRUS) guided needle biopsy is currently the clinical standard routine for diagnosis of prostate cancer. The prostate under TRUS procedure possesses different orientation and shape from its presentation in MRI procedure. Therefore, registration of suspicious tumor sites identified...

Stretchable electronics system is an emerging technology for next-generation electronics. These type of stretchable system can geometrically accommodate large mechanical deformations without imparting significant strains and stress in the materials themselves. Potential uses include flexible sensors, transmitters and new photovoltaic and medical de...

Significance Conventional electroencephalogram (EEG) recording systems, particularly the hardware components that form the physical interfaces to the head, have inherent drawbacks that limit the widespread use of continuous EEG measurements for medical diagnostics, sleep monitoring, and cognitive control. Here we introduce soft electronic construct...

Transient electronics represents an emerging class of technology that exploits materials and/or device constructs that are capable of physically disappearing or disintegrating in a controlled manner, at programmed rates or times. Inorganic semiconductor nanomaterials such as silicon nanomembranes/nanoribbons provide attractive choices for transisto...

Non-invasive, biomedical devices have the potential to provide important, quantitative data for the assessment of skin diseases and wound healing. Traditional methods either rely on qualitative visual and tactile judgments of a professional and/or data obtained using instrumentation with forms that do not readily allow intimate integration with sen...

On page 906, U. Paik, J. A. Rogers, and co-workers present materials and device designs for a 'skin-like' class of electronic device with near-field communication (NFC) capabilities. The key unique features are ultrathin construction, ultralow modulus, and an ability to accommodate large strain deformation for seamless, conformal contact with and r...

This paper presents materials and designs for an ultrathin, stretchable class of device that is capable of lamination onto the surface of the skin, for wireless determination of dielectric and surface strain properties. The sensor exploits LC resonators with capacitive electrodes whose radio frequency characteristics change with variations in skin...

J. A. Rogers and co‐workers present an ultrathin, skin‐like device for the wireless measurement of the dielectric properties and deformations of the skin. The construction exploits LC resonators with capacitive electrodes that are responsive to skin properties. The material designs offer the potential for compact, epidermal, wireless systems in app...

In nature, arthropods have a remarkably sophisticated class of imaging systems, with a hemispherical geometry, a wideangle field of view, low aberrations, high acuity to motion and an infinite depth of field. There are great interests in building systems with similar geometries and properties due to numerous potential applications. However, the est...

In the island-interconnect design, the device islands connected by interconnects are mounted on a soft elastomeric substrate. The out-of-plane motion of interconnects accommodates the deformation applied to the system, enabling stretchable feather in electronics. The areal coverage, however, decreases due to the presence of interconnects. This prob...

Stretchable electronics has been applied to balloon catheters for high-efficacy ablation, with tactile sensing integrated on the surface, to establish full and conformal contact with the endocardial surface for elimination of the heart sink caused by blood flow around their surfaces. The balloon of the catheter folds into uniform ‘clover’ patterns...

Compound eyes in arthropods demonstrate distinct imaging characteristics from human eyes, with wide angle field of view, low aberrations, high acuity to motion and infinite depth of field. Artificial imaging systems with similar geometries and properties are of great interest for many applications. However, the challenges in building such systems w...

Laying wires in fractal patterns could improve stretchable electronics. Devices such as wearable sensors require circuits that can withstand stretching. A team led by John Rogers at the University of Illinois at Urbana-Champaign bonded wires in fractal motifs to elastic materials (pictured). Fractals are complex patterns that, when divided into sm...

Means for high-density multiparametric physiological mapping and stimulation are critically important in both basic and clinical cardiology. Current conformal electronic systems are essentially 2D sheets, which cannot cover the full epicardial surface or maintain reliable contact for chronic use without sutures or adhesives. Here we create 3D elast...

Stretchable electronics provide a foundation for applications that exceed the scope of conventional wafer and circuit board technologies due to their unique capacity to integrate with soft materials and curvilinear surfaces. The range of possibilities is predicated on the development of device architectures that simultaneously offer advanced electr...

Precision thermometry of the skin can, together with other measurements, provide clinically relevant information about cardiovascular health, cognitive state, malignancy and many other important aspects of human physiology. Here, we introduce an ultrathin, compliant skin-like sensor/actuator technology that can pliably laminate onto the epidermis t...

This work presents digital cameras that resemble, both structurally and functionally, apposition-type compound eyes of daylight insect. Hemispherical imagers with 180 artificial ommatidia yield 160 degree field of view and nearly infinite depth-of-field.

In arthropods, evolution has created a remarkably sophisticated class of imaging systems, with a wide-angle field of view, low aberrations, high acuity to motion and an infinite depth of field. A challenge in building digital cameras with the hemispherical, compound apposition layouts of arthropod eyes is that essential design requirements cannot b...

Mechanics models are developed for an imbricate scale design for stretchable and flexible electronics to achieve both mechanical stretchability and high fill factors (e.g., full, 100% areal coverage). The critical conditions for self collapse of scales and scale contact give analytically the maximum and minimum widths of scales, which are important...

Curved surfaces, complex geometries, and time-dynamic deformations of the heart create challenges in establishing intimate, nonconstraining interfaces between cardiac structures and medical devices or surgical tools, particularly over large areas. We constructed large area designs for diagnostic and therapeutic stretchable sensor and actuator webs...

Notched islands on a thin elastomeric substrate serve as a platform for dual-junction GaInP/GaAs solar cells with microscale dimensions and ultrathin forms for stretchable photovoltaic modules. These designs allow for a high degree of stretchability and areal coverage, and they provide a natural form of strain-limiting behavior, helping to avoid de...

The cover picture shows a composite image of two colorized scanning electron microscopy images. One illustrates an overlapping assembly of microscale silicon, photonic, and plasmonic plates on an elastomeric substrate. This imbricate layout is often found in nature–the scales of snake skin or a butterfly wing, but never in man-made microsystems. Ap...

Spatially overlapping plates in tiled configurations represent designs that are observed widely in nature (e.g., fish and snake scales) and man-made systems (e.g., shingled roofs) alike. This imbricate architecture offers fault-tolerant, multifunctional capabilities, in layouts that can provide mechanical flexibility even with full, 100% areal cove...

Stretchable and flexible electronics offer the performance of conventional wafer-based systems but can be stretched like a rubber band, twisted like a rope, and bent over a pencil. Such a technology offers new application opportunities, in areas of surgical and diagnostic implements that naturally integrate with the human body to provide advanced c...

Electronic systems with large stretchability have many applications. A precisely controlled buckling strategy to increase the stretchability has been demonstrated by combining lithographically patterned surface bonding chemistry and a buckling process. The buckled geometry was assumed to have a sinusoidal form, which may result in errors to determi...

Developing advanced surgical tools for minimally invasive procedures represents an activity of central importance to improving human health. A key challenge is in establishing biocompatible interfaces between the classes of semiconductor device and sensor technologies that might be most useful in this context and the soft, curvilinear surfaces of t...

Applications of ferroelectric ceramics, ranging from components for sensors, memory devices, microelectromechanical systems, and energy convertors, all involve planar and rigid layouts. The brittle nature of such materials and their high-temperature processing requirements limit applications to devices that involve only very small mechanical deform...

Strategies are presented for achieving, simultaneously, both large areal coverage and high stretchability by using elastomeric substrates with surface relief in geometries that confine strains at the locations of the interconnections, and away from the devices. The studies involve a combination of theory and experiment to reveal the essential mecha...

The cover image shows a stretchable photovoltaic module consisting of ultrathin, inorganic solar cells interconnected in mesh-like geometries and mounted onto structured elastomeric substrates, as reported by Yonggang Huang, John A. Rogers, and co-workers on p. 986. Mechanical deformations are accommodated by the flexible interconnects of the mesh...

Current technology development in light emitting diodes has enabled high efficiency operation, low energy consumption and lifetimes, thereby creating new possibilities in conventional display and lighting industry. Recent work is also creating more unusual uses in biomedicine and in sensing applications, where conformal contact over curvilinear sur...

Imaging systems that exploit arrays of photodetectors in curvilinear layouts are attractive due to their ability to match the strongly nonplanar image surfaces (i.e., Petzval surfaces) that form with simple lenses, thereby creating new design options. Recent work has yielded significant progress in the realization of such "eyeball" cameras, includi...

Inorganic light-emitting diodes and photodetectors represent important, established technologies for solid-state lighting, digital imaging and many other applications. Eliminating mechanical and geometrical design constraints imposed by the supporting semiconductor wafers can enable alternative uses in areas such as biomedicine and robotics. Here w...

Reversible control of adhesion is an important feature of many desired, existing, and potential systems, including climbing robots, medical tapes, and stamps for transfer printing. We present experimental and theoretical studies of pressure modulated adhesion between flat, stiff objects and elastomeric surfaces with sharp features of surface relief...

The analytical solution is obtained for a semi-infinite linear elastic solid with a sinu-soidal, "wavy" surface profile subject to applied strain. The amplitude A of a deformed wavy surface is related to the initial amplitude A(0) and the applied strain epsilon(a) through the simple expression A=A(0)(1 - epsilon(a)). This relation is confirmed inde...

Materials and design strategies for stretchable silicon integrated circuits that use non-coplanar mesh layouts and elastomeric substrates are presented. Detailed experimental and theoretical studies reveal many of the key underlying aspects of these systems. The results shpw, as an example, optimized mechanics and materials for circuits that exhibi...

We present various stretchable highperformance CMOS circuit demonstrations on unconventional substrates, such as fabric, vinyl, leather, and paper. Electronics on such substrates, especially paper, open up new and important application possibilities for electronics. Theoretical analysis reveals the underlying mechanics of these systems; electrical...

The cover shows a silicon integrated circuit on a paper substrate. The system consists of ultrathin devices electrically and mechanically interconnected with stretchable, serpentine ribbons. A low modulus elastomeric adhesive isolates the circuit from strains associated with bending and folding the paper. This strategy provides a route to high qual...

We have developed methods for creating microscale inorganic light-emitting diodes (LEDs) and for assembling and interconnecting them into unusual display and lighting systems. The LEDs use specialized epitaxial semiconductor layers that allow delineation and release of large collections of ultrathin devices. Diverse shapes are possible, with dimens...