S1E1

Abstract:

Soft biological tissues typically consist of large amounts of water molecules (30-80 wt%) and networks of flexible polymers. The water molecules provide a liquid-like medium in which other molecules migrate and react. The polymer networks enable a solid-like structure of properties such as modulus, toughness, and fatigue resistance. These tissues often have complex shapes and heterogeneous structures. The forms and functions of biological tissues are always mimicked to enable diverse applications, such as tissue engineering, regenerative medicine, and soft robots. 3D printing technologies have opened engaging possibilities to manufacture complex shaped soft structures for the purpose of bionics. Myriads of approaches have been developed, such as extrusion printing and stereolithography. However, the 3D printed soft materials still face several fundamental challenges: fatigue and adhesion between heterogeneous materials. The advance in this field will greatly expand the function and application of 3D printed soft materials. We will show their applications in shape morphing, ionotronics and biomedical engineering.

Abstract:

A diversity of chemical motors based on Marangoni propulsive forces has been developed in recent years. However, most motors are non-functional due to poor performance, a lack of control, and the use of toxic materials. To overcome these limitations, we have developed multifunctional and biodegradable self-propelled motors from structural proteins and an anesthetic metabolite. The protein motors surpass previous reports in performance output and efficiency by several orders of magnitude, and they offer control of their propulsion modes, speed, mobility lifetime, and directionality by regulating the protein nanostructure via local and external stimuli, resulting in programmable and complex locomotion. We demonstrate diverse functionalities of these motors in environmental remediation, microrobot powering, and cargo delivery applications. These versatile and degradable protein motors enable design, control, and actuation strategies in microrobotics as modular propulsion sources for autonomous operation.

Abstract:

Adhering two surfaces together to form an integrated structure is one of the most fundamental ways of processing materials. Not surprisingly, various methods and strategies of adhesion have been workhorses that drive countless innovations and technological breakthroughs in modern engineering. For example, our daily objects and structures such as cell phones, laptops, houses, and even cars are full of various types of adhesives and glues, without which we may not be able to enjoy slim and seamless designs and integrity of these modern technological marvels. However, these magical adhesives mostly fail, often exhibiting strikingly poor adhesion, when they meet wet surfaces like biological tissues and hydrogels. This notable incompatibility of existing adhesives to wet surfaces originates from the fact that most existing adhesive technologies are designed for “dry” conventional engineering materials such as ceramics, metals, glasses, and rubbers. Despite the lack of good existing solutions, the importance of robust adhesion for wet materials is ever increasing with high unmet demand in a broad range of fields.

In this talk, I will introduce a series of wet adhesion technologies to address this lingering challenge with a focus on the mechanism, design principle, and translation of each technology to real-world applications. In specific, I will cover three key aspects of translational wet adhesion technologies including 1) fundamental mechanisms for rapid and robust wet adhesion, 2) novel methods for diverse materials such as engineering solids, hydrogels, conducting polymers, and biological tissues, and 3) real-world applications of wet adhesion technologies. At the end of the talk, future perspectives for translational wet adhesion technologies will be briefly discussed including the remaining challenges and opportunities.