What are NEMS
Nanoelectromechanical systems (NEMS) are a class of devices integrating electrical and mechanical functionality on the nanoscale. NEMS form the next logical miniaturisation step from so-called microelectromechanical systems, or MEMS devices. NEMS typically integrate transistor-like nanoelectronics with mechanical actuators, pumps, or motors, and may thereby form physical, biological, and chemical sensors. The name derives from typical device dimensions in the nanometer range, leading to low mass, high mechanical resonance frequencies, potentially large quantum mechanical effects such as zero point motion, and a high surface-to-volume ratio useful for surface-based sensing mechanisms. Applications include accelerometers and sensors to detect chemical substances in the air.
What are MEMS?
Microelectromechanical systems (MEMS, also written as micro-electro-mechanical, MicroElectroMechanical or microelectronic and microelectromechanical systems and the related micromechatronics and microsystems) is the technology of microscopic devices, particularly those with moving parts. It merges at the nano-scale into nanoelectromechanical systems (NEMS) and nanotechnology. MEMS are also referred to as micromachines in Japan, or micro systems technology (MST) in Europe.
MEMS are made up of components between 1 and 100 micrometers in size (i.e., 0.001 to 0.1 mm), and MEMS devices generally range in size from 20 micrometres to a millimetre (i.e., 0.02 to 1.0 mm), although components arranged in arrays (e.g., digital micromirror devices) can be more than 1000 mm2.They usually consist of a central unit that processes data (an integrated circuit chip such as microprocessor) and several components that interact with the surroundings (such as microsensors). Because of the large surface area to volume ratio of MEMS, forces produced by ambient electromagnetism (e.g., electrostatic charges and magnetic moments), and fluid dynamics (e.g., surface tension and viscosity) are more important design considerations than with larger scale mechanical devices. MEMS technology is distinguished from molecular nanotechnology or molecular electronics in that the latter must also consider surface chemistry.
MEMS Fabrication.
MEMS are generally made by using basic fabrication techniques and materials of microelectronics, thin layers of materials are deposited on the base and selectively etched away leaving the 3-dimensional structures in this way MEMS mechanical and electrical elements can be constructed. Electrical elements on the chip process the data while Mechanical elements act in response to the data.
Most commonly used techniques in MEMS are Photolithography, Bulk micromachining, surface micromaching, LIGA etc.
Bio-MEMS the Life saviours...!!
One of the fruits of wisdom is to which humanity is debited is for the Bio-integration of sensors into everyday lives, with which the monitoring and diagnosis of an inherent malady are accomplished. The development of immunoassays and integration with MEMS (Micro Electro Mechanical systems/sensors) made it very effective in Non-invasive, point-of-care testing. And pushing the limits further with the power of Nanotechnology, the functionalized nano-surfaces enhanced the optimization and selectivity of the sensor. But there exists technological challenges like stability and the life of the sensors, the sustainability of the device implanted within the body is one of the key factors for the effectiveness. Recent technological advancements led to the breakthroughs where enzymes and immunoassays can be replaced by Nano-particles providing the same kind of catalytic activity as the former. Integrating such technology with the novel MEMS led to the genesis of a new class of Health monitoring devices with much longer sustainability and enhanced bio compatibility, and the devices are being miniaturized to the Millimeter scale integrated with fully functional telemetry and memory modules, and the best part is the user no longer feels the presence of Sensor, which continuously diagnoses and monitors. The unexpected conditions like Transient Ischemic Attacks, hypoglycemia, silent ischemia, etc., which could occur at night during sleep could be very fatal leading to death...!! Such kinds of events could be averted by the implantable Bio-MEMS-sensors, which would detect the symptoms and the alert the patient and his family, and even call the SOS - medical personal in an event of stroke and the save the lives. Bio-MEMS the life saviors..!!!
MEMS - Providing new senses for the Impaired
It's not in a distant future where MEMS would be used to provide new senses for the impaired. With development of state of the art MEMS enabling detection of the ambient physical quantities with higher precision and accuracy, sensors like MEMS embedded in prosthetics, capacitive MEMS (simulates the sense of touch by providing pressure as feedback at the point of interaction) etc., could provide feedback to Sensory nerves through electrical impulses stimulating a real-time sensory stimulus mimicking the biological stimuli. Considering the breakthroughs in the development of AI it would not be a scientific fantasy anymore where humanoid robots (which employ MEMS analogous to human senses) would take positions in production lines, which lack natural intuition like humans and purely depend on the math based on feedback provided by embedded sensors, there is a need for further research in parallel areas like evaluating reliability issues in MEMS arising due to uncertainties during fabrication like over-etching, geometrical offset and in evaluating Mechanical characterization of Polysilicon which is the most widely used material in fabrication of MEMS.