Kaiyan Qiu

Tactile perception arises from coordinated activation of mechanoreceptors and thermoreceptors, yet most wearable haptic technologies primarily stimulate mechanoreceptors. Thermal haptic interfaces remain constrained by rigid heat sinks, unstable hydrogels, or insufficient thermal management; thus compact integration of active thermal and mechanical actuation in a skin‐conformable platform remains difficult. Here, we present a compliant thermal haptic device that enables bidirectional heating and cooling without rigid heat dissipation structures. The device uses a polymer matrix filled with hexagonal boron nitride and phase‐change materials to form dynamic, effective thermal pathways. A soft heat sink based on gallium‐polymer composites provides stable thermal regulation while preserving compliance. A gallium‐based soft electromagnetic actuator is further integrated for mechanical haptic feedback. The thermo‐ and mechano‐haptic components are connected through a kirigami‐inspired architecture, enabling simultaneous mechanical and thermal feedback in a stretchable platform. Preliminary user tests show that multimodal feedback improves material‐recognition accuracy to 96.4%, compared with 74.9% for mechanical‐only cues and 87.6% for thermal‐only cues. These results offer materials and integration strategies for skin‐integrated multimodal haptics, with potential applications in VR/AR, telepresence, prosthetics, and rehabilitation.

Flexible electrochemical sensors have emerged as a promising platform for real-time, noninvasive health monitoring, driven by rapid advances in nanomaterials, fabrication methods, and system integration. Over the past decade, substantial efforts have focused on improving their mechanical flexibility, analytical sensitivity, and biocompatibility, thereby expanding their potential in clinical diagnostics and personalized healthcare. Despite this progress, several key challenges continue to hinder practical translation. This review provides a comprehensive overview of recent advances in flexible electrochemical sensors, with particular emphasis on nanomaterial engineering, device fabrication strategies, and biomedical applications. Representative applications in sweat, interstitial fluid, tears, and saliva are summarized and critically discussed. The review also examines current limitations, including challenges in sample collection, the variable reliability of biofluid biomarkers, and interference from complex biological matrices. Finally, future perspectives are presented on the integration of artificial intelligence and machine learning with flexible electrochemical sensors to enable improved data interpretation, interference correction, and more accurate biomarker identification in complex biofluids.

Heart disease remains a major cause of morbidity and mortality in the United States, accounting for roughly 20% of all deaths. Minimally invasive procedures have been used to treat cardiovascular diseases; however, the heart's anatomical complexity and dynamics require proper hands‐on training on patient‐specific presurgical models to reduce procedural errors. Existing dynamic heart models often rely on animal cardiac tissues to support pumping mechanics, introducing ethical and policy concerns. Fully synthetic heart models offer an alternative by using actuation devices to reproduce cardiac circulation and contraction, yet accurately replicating the full dynamics of the heart remains challenging. This research presents a 3D‐printed dynamic heart model representing left‐side anatomy (atrium, ventricle, and mitral valve) to support minimally invasive procedures. Soft material 3D‐printing is employed to replicate key anatomical features. Sutures anchor the ventricle to the mitral valve, replicating chordae tendineae‐like structures, adding physiological realism and structural complexity. McKibben actuators are embedded within the myocardial walls, mimicking ventricular contraction and realistic mitral valve motion. Customized flexible pressure sensors are designed and incorporated to monitor pressure changes inside the model. These novel features enable the model to function as a platform for hemodynamic studies and simulation of edge‐to‐edge repair to mitigate atrioventricular valve regurgitation.

Wearable electrochemical sensors have aroused tremendous attention due to their great potential for in situ and continuous assessment for glucose monitoring. The conventional fingerstick test is the easiest and most efficient method for glucose evaluation, but it is invasive and painful. Here we introduce a wearable and user-friendly microneedle-based electrochemical sensor, fabricated via resin 3D printing with an affordable desktop 3D printer and featuring a single-atom nanozyme-modified electrode, offering high sensitivity and superior selectivity for glucose monitoring. This minimally invasive electrochemical sensor demonstrates the capability to extract artificial interstitial fluid using hollow microneedles and a finger-activated pump, enabling continuous monitoring of dynamic glucose concentration changes. This electrochemical sensor exhibits remarkable sensitivity and selectivity, with a linear range of 0.1 μM to 50 mM and a limit of detection of 0.285 μM, attributed to the incorporation of single-atom nanozymes with peroxidase-like enzymatic activity. The glucose concentration data are wirelessly transmitted to a smartphone application in real time, offering user-friendly access and facilitating remote monitoring. The described electrochemical sensor presents the possibilities for point-of-care health monitoring applications.

Medical errors are one of the leading death causes in the United States, becoming a serious concern in clinical surgeries. Although full elimination of medical errors is unattainable, proper surgical planning and rehearsals on presurgical artificial organ models can reduce the error occurrences. However, current organ models miss multiple important features, such as a lack of tissue-mimicking properties and quantitative sensing feedback, significantly limiting their capabilities in advanced surgical planning and rehearsal. Therefore, the design and development of new methods and customized inks to fabricate patient-specific 3D-printed artificial organ models with accurate tissue-mimicking sensation and real-time operation feedback can be greatly beneficial to surgical applications and outcomes. This chapter introduces relevant fabrication, properties, characterization, and applications of 3D-printed patient-specific prostate models with physical properties of tissue and integrated soft electronic sensors.

Wearable electrochemical sensors have aroused tremendous attention due to their great potential for in situ and continuous assessment for glucose monitoring. Conventional fingerstick test is the easiest and most efficient method for glucose evaluation, but invasive and painful. Here we introduce a wearable and user-friendly microneedle-based electrochemical sensor, fabricated via resin 3D printing and integration of a single-atom nanozyme-modified electrode, offering excellent biocompatibility, high sensitivity and superior selectivity for glucose monitoring. This minimally invasive electrochemical sensor demonstrates the capability to extract artificial interstitial fluid using biocompatible hollow microneedles and a finger-activated pump, enabling continuous monitoring of dynamic glucose concentration changes. This electrochemical sensor exhibits remarkable sensitivity and exceptional selectivity, with a linear range of 0.1 μM to 50 mM and a limit of detection of 0.059 μM, attributed to the incorporation of single-atom nanozymes with peroxidase-like enzymatic activity. The glucose concentration data are wirelessly transmitted to a mobile app in real time, offering user-friendly access and facilitating remote monitoring. The described electrochemical sensor presents the possibilities for point-of-care health monitoring applications.

A major intent of scientific research is the replication of the behaviour observed in natural spaces. In robotics, these can be through biomimetic movements in devices and inspiration from diverse actions in nature, also known as bioinspired features. An interesting pathway enabling both features is the fabrication of soft actuators. Specifically, 3D‐printing has been explored as a potential approach for the development of biomimetic and bioinspired soft actuators. The extent of this method is highlighted through the large array of applications and techniques used to create these devices, as applications from the movement of fern trees to contraction in organs are explored. In this review, different 3D‐printing fabrication methods, materials, and types of soft actuators, and their respective applications are discussed in depth. Finally, the extent of their use for present operations and future technological advances are discussed.