Metamaterials that Mechanically Compute via Nonlinear Deformations

In this work, we introduce and compare two fundamentally different ways that metamaterials can leverage the nonlinear elastic deformations of their constituent flexible elements to perform mechanical computations—digital and analog. The ability to calculate in a purely mechanical way is becoming increasingly important for critical technologies to operate during power outages or in harsh conditions that are not compatible with electronics (e.g., radiation rich, extreme temperature, or chemically corrosive environments). Unfortunately, traditional mechanical computers, which rely on rigid components (e.g., gears, cams, shafts), lack the necessary accuracy and precision to reliably perform calculations due to the backlash, hysteresis, and friction, inherent in their contact-based sliding or rolling joints. Moreover, such systems are, of necessity, relatively large, heavy, dangerous, and noisy. Thus, researchers have begun to recognize that compliant versions of mechanical computers are necessary to sidestep these issues and enable metamaterials that can perform many complex mechanical calculations in a small space with micro/nano-sized features that can be additively fabricated. Such metamaterials can be designed to perform computations using either a digital or an analog approach. The digital approach leverages flexure-based bi-stable memory bits and logic gates joined together to perform the calculations using discrete states of deformation, while the analog approach uses a single one-piece structure that deforms according to continuous input displacements and forces. We will provide metamaterial examples that embody both approaches and will compare their advantages and disadvantages to provide a vision of a future that leverages both approaches simultaneously to enable practical metamaterials that perform computations in environments where electronics fail.