YICHAO SHI | 施一超

Yichao Shi, James H Pikul

Bioinspired mobile robots move with comparable efficiency to their animal counterparts but lag by more than an order of magnitude in system-level energy density because of battery limitations. This Review quantifies this energy gap, evaluates hardware strengths and current battery weaknesses, and proposes benchmarking frameworks for future technologies. Using Spot as a case study, we identify the battery chemistries needed to match the energy storage in animals and propose technologies to unleash robotic endurance.

Muqing Ren*, Yichao Shi*, Langqiu Xiao, Anqian Sun, Eric Johnston, Thomas E Mallouk, Mark Allen, James H Pikul

Internet of Things (IoT) devices and small robots would benefit from higher-energy-density and disposable primary Al–air batteries, but corrosion and side reactions on the Al anode limit the widespread application of this chemistry. This paper studies how the physical and chemical characteristics of double-network hydrogel (DNH) electrolytes affect the anode oxidation, discharge morphology, and performance of Al–air batteries. The chemically crosslinked and physical–chemical crosslinked DNHs were made from biodegradable materials and showed enhanced corrosion inhibition compared to aqueous KOH solution, reducing the corrosion rate by 58% to 21 mmpy. An Al–air battery with a PVA-PAAM DNH extracted over 300 mAh cm−2 from Al at 10 mA cm−2.

Yichao Shi* Muqing Ren*, Anqian Sun, Eric D Johnston, Mark G Allen, James H Pikul

Soft robots and wearable technologies benefit significantly from stretchable batteries, yet the rigid nature of high-capacity electrodes creates large trade-offs in battery performance and stretchability. This study introduces a new approach for realizing stretchable batteries by allowing the electrodes to slide along a stretchable electrolyte. When the sliding-electrodes battery is stretched, the forces are transmitted through the hydrogel electrolyte and elastomeric enclosure, while the rigid electrodes slide relative to the hydrogel to maintain interfacial contact. The sliding-electrodes approach allows 100% of the unstretched battery area to be covered by thick electrodes so that the battery areal capacity and power are improved by up to 10X of prior stretchable designs. Three metal-air batteries achieve areal capacities of up to 104 mWh cm−2. Further mechanical testing, electrochemical characterization, and integration into soft robotic systems demonstrate the potential of these stretchable batteries in practical applications. The sliding-electrodes battery can stably power multiple servo motors and sensing circuits under stretching, twisting, bending, and after impact.

Junyu Chen,Yichao Shi, Binbin Ying, Yajie Hu, Yan Gao, Sida Luo, Xinyu Liu

Flexible and stretchable heaters are increasingly recognized for their great potential in wearable thermotherapy to treat muscle spasms, joint injuries and arthritis. However, issues like lengthy processing, high fabrication cost, and toxic chemical involvement are obstacles on the way to popularize stretchable heaters for medical use. Herein, using a single-step customizable laser fabrication method, we put forward the design of cost-effective wearable laser-induced graphene (LIG) heaters with kirigami patterns, which offer multimodal stretchability and conformal fit to the skin around the human body. First, we develop the manufacturing process of the LIG heaters with three different kirigami patterns enabling reliable stretchability by out-of-plane buckling. Then, by adjusting the laser parameters, we confirm that the LIG produced by medium laser power could maintain a balance between mechanical strength and electrical conductivity. By optimizing cutting-spacing ratios through experimental measurements of stress, resistance and temperature profiles, as well as finite element analysis (FEA), we determine that a larger cutting-spacing ratio within the machining precision will lead to better mechanical, electrical and heating performance. The optimized stretchable heater in this paper could bear significant unidirectional strain over 100% or multidirectional strain over 20% without major loss in conductivity and heating performance. On-body tests and fatigue tests also proved great robustness in practical scenarios. With the advantage of safe usage, simple and customizable fabrication, easy bonding with skin, and multidirectional stretchability, the on-skin heaters are promising to substitute the traditional heating packs/wraps for thermotherapy.

Yichao Shi, Zhimin Jiang, James H Pikul

Organisms have evolved many simple yet effective muscular movements. Of these, peristaltic wave motion is among the most prolific and can be found across organism scales and in a variety of organs that transport objects or provide locomotion. Several robotic platforms have mimicked peristaltic movement, which resembles soliton propagation; however, the complexity of integrating multiple sequential actuators and the fragility of these systems have limited their practical application. In this work, we demonstrate the potential of cascading dominoes to realize soliton-like wave movements that can transport objects and locomote with only two actuators. Unlike conventional domino series where falling dominoes produce a soliton at the collapsing frontier, we added a revolute joint on each domino to ensure all the dominoes stack continuously, which inherently changes the soliton wave shape. We show how domino geometry determines the wave shape of the soliton, both analytically and experimentally, and how actuator speed affects the wave speed. Inspired by peristaltic wave motion in living organisms, we used the cascading dominoes to move objects through an artificial esophageal conduit and build a “mantis shrimp” crawler. Cascading dominoes enable a new type of actuator mechanism and provide new opportunities for robotic motion.

Sahab Babaee, Yichao Shi, Saeed Abbasalizadeh, Siddartha Tamang, Kaitlyn Hess, Joy E Collins, Keiko Ishida, Aaron Lopes, Michael Williams, Mazen Albaghdadi, Alison M Hayward, Giovanni Traverso

Implantable drug depots have the capacity to locally meet therapeutic requirements by maximizing local drug efficacy and minimizing potential systemic side effects. Tubular organs including the gastrointestinal tract, respiratory tract and vasculature all manifest with endoluminal disease. The anatomic distribution of localized drug delivery for these organs using existing therapeutic modalities is limited. Application of local depots in a circumferential and extended longitudinal fashion could transform our capacity to offer effective treatment across a range of conditions. Here we report the development and application of a kirigami-based stent platform to achieve this. The stents comprise a stretchable snake-skin-inspired kirigami shell integrated with a fluidically driven linear soft actuator. They have the capacity to deposit drug depots circumferentially and longitudinally in the tubular mucosa of the gastrointestinal tract across millimetre to multi-centimetre length scales, as well as in the vasculature and large airways. We characterize the mechanics of kirigami stents for injection, and their capacity to engage tissue in a controlled manner and deposit degradable microparticles loaded with therapeutics by evaluating these systems ex vivo and in vivo in swine. We anticipate such systems could be applied for a range of endoluminal diseases by simplifying dosing regimens while maximizing drug on-target effects through the sustained release of therapeutics and minimizing systemic side effects.

Sahab Babaee, Simo Pajovic, Ahmad Rafsanjani, Yichao Shi, Katia Bertoldi, Giovanni Traverso

Falls and subsequent complications are major contributors to morbidity and mortality, especially in older adults. Here, by taking inspiration from claws and scales found in nature, we show that buckling kirigami structures applied to footwear outsoles generate higher friction forces in the forefoot and transversally to the direction of movement. We identified optimal kirigami designs capable of modulating friction for a range of surfaces, including ice, by evaluating the performance of the dynamic kirigami outsoles through numerical simulations and in vitro friction testing, as well as via human-gait force-plate measurements. We anticipate that lightweight kirigami metasurfaces applied to footwear outsoles could help mitigate the risk of slips and falls in a range of environments.