Table 4.

A summary of reported mechanical metamaterial devices for applications related to information processing, along with their key advantages

		Category	Characteristics	Potential applications	Advantages	Ref.
Logic gates	Resonant clock network	Wave-based	Designed with an infinite-wavelength zeroth-order resonance mode and utilizes the ultralow Joule loss of superconductors at microwave frequencies	Scaling the power distribution network in superconductor digital circuits to CMOS levels of integration	Metamaterial resonant clock network for energy-efficient power delivery to large superconducting digital systems	208
	Terahertz (THz) metamaterials		Programmable THz metamaterials with cut-wire resonator (CWR) sandwiched two face-to-face split-ring resonators.	Stable polarization switch	Coding digits can be switched by changing the vertical distance of the CWR	209
	Terahertz (THz) metamaterials		MEMS-based metadevices based on switchable winding-shaped cantilever metamaterial for active logical modulation	Enlarging the operating frequency range, which provides various possibilities in multifunctional switching, active logical modulating, and optical computing applications	Better optical switching performance, realizing a high-efficient optical switch and programmable devices	210
	Boolean mechanical logic	Mechanical-based	Performing Boolean logic operation based on the buckling response of 3D unit cells	Complementing the semiconductor electronics for operation in harsh environments (e.g., high radiation fields in nuclear reactors and hot cell laboratories)	Mechanical logic devices to perform various functions (e.g., Boolean logic, sensing or actuating)	23,160,211
	Surface plasmon polaritons	Mechanical-based	Coding and programmable designer plasmon polaritons by an ultrathin corrugated metallic strip loaded with active devices and a digital system	Switching polaritons in real time using a single prototype and the digital control system	Digital-analog functions of logical gates based on 1-bit coding, digital phase shifters based on 2-bit coding, and slow waves based on 4-bit coding	212
Computing	Mathematical operations	Wave-based	Metamaterial blocks to perform mathematical operations by propagating an impinging wave through these blocks	Direct, ultrafast, wave-based analog computation, equation solving, and signal processing at the hardware level	Wave-based computing systems significantly thinner than conventional lens-based optical signal and data processors	213
Image processing	Computational imaging		Low-profile aperture for microwave imaging without lenses, moving parts or phase shifters	Combing computational imaging approach with custom aperture hardware to perform compression in the physical layer	Extending the microwave and millimeter-wave imaging capabilities by the small form factor and lack of moving parts	214
Data processing	Data memory	Electromagnetic-based	Tileable mechanical metamaterial with stable memory at the unit-cell level by arraying physical binary elements (m-bits) with clearly delineated writing and reading phases	Stable memory and on-demand programmability of mechanical properties	Distinctly different mechanical response that is fully elastic and can be reversibly cycled	128