We define the Nano/Micro Electro Mechanical System (N/MEMS) as a miniaturized electromechanical system, in which small-sized mechanical, thermofluidic, optoradiative and biochemical devices and structures are combined with electrical devices to achieve improved performance or new functions in multi-modal nano/micro regimes. The driving forces and major advantages of the miniaturization (Fig.1) include the improvement of the 3P (Price, Performance, and Power consumption) of electromechanical systems.
|Fig.1 Driving forces for miniaturization.
||Fig.2 Nano/Micro transduction
among multi-modal realms.
From the functional point of view, N/MEMS performs nano/micro-scale transduction (Fig.2) among mechanical, electrical, optoradiative, thermofluidic and biochemical realms. We consider the media or matters of the nano/micro transduction as the carriers containing mechanical, electrical, optoradiative, thermofluidic or biochemical information. The concept of the multi-modal media has been extracted from the historical review (Table 1) of the technology revolutions in the past, present and future centuries.
Table 1. Comparison of the technology revolutions and eras: past, present and future
||Metal refining and manufacturing technology
| Nano/Micromachining technology
||Bulk metal (steel)
|| Semiconductor + Film metal + Polymeric materials
||Engine and machinery
||Integrated circuits and memory
||Multi-modal processors and transducers
|Function of Products
||Power conversion and management
||Electrical signal processing and management
||Nano/Micro transduction and cognition
|Figure of Merit
||Strength / Weight
||Speed / Power
|| Diversity X Capacity X Speed / Power
In Table 1 we classify the technology eras in the view of energy utilization. Before the industrial revolution, Human utilized natural energy in unmodified forms (i.e. as it was). Human simply used the thermal energy of fire for cooking and heating, and the radiative energy for lighting, respectively. The industrial revolution era, however, is featured by the invention of the methods to modify or convert the form of energy for specific applications. Steam engine converts the thermal energy of fire into that of steam, eventually obtaining the mechanical energy to move things. The electronics revolution era is characterized by the use of electrical energy as information carrier, while the electrical energy in the industrial revolution era had been used as a power carrier. In the future technology era, the energy of non-electrical modalities, including mechanical, optoradiative, thermofluidic, and biochemical modalities, will be utilized as information carriers.
Now we attempt to interpolate the characteristics of the past and present technology eras (Table 1); thus extraplating those of the future technology era as follows. In the industrial revolution era, heavy or mechanical industry had been developed on the basis of the metal refining and manufacturing technologies. Major products in the industrial revolution era had included the engine and machinery for the energy conversion and power management, whose performance merits had been defined by the strength of the products using the minimum weight of materials. In the electronics revolution era, however, electronics industry has been developed rapidly with the advance of semiconductor and microelectronics fabrication technology. The major function of the electronics devices includes the high-speed management of electrical information using the minimum electrical power. At this moment, knowledge industry is projected to be dominated in next technology era, where nano/micro-machining technology is expected to play a key role in the development of multi-modal devices and systems, made of silicon, metallic and/or polymeric film materials. The devices and products in the knowledge era are required to manage the various forms of multi-modal information (Fig.1) for high-speed, low-power and multi-modal functions