by Pasindu Hansa Kumara
Introduction to MEMS Technologies
Microelectromechanical systems (MEMS) are micro devices or integrated systems related to electrical, mechanical systems developed using batch processing techniques compatible with integrated circuits (IC) and ranging in size from micrometers to millimeters / nanometers to micrometers display. These micro-scale systems can sense, control and work individually or in matrices to solve macroscale problems.
MEMS functional work elements are microstructures, micro sensors, micro actuators, and microelectronics. Micro actuators are devices that convert electrical signals into physical outputs, and microsensors convert a measured mechanical signal into a microscale electrical signal. Microelectronic integrated circuits can be thought of as the brain of a MEMS system. Sensors are used to gather information from the environment by measuring mechanical, biological, chemical, thermal and magnetic phenomena. Then the electronics process the information/data sensed from the sensors and, through some decisions, instruct the actuators to react by moving, regulating, pumping, positioning, and filtering to control the environment for a certain desired result.
MEMS-based force sensors have been developed for many applications, including in robotic systems, minimal invasive surgery, and the manipulation of robot hands. The piezoresistive-type force sensor, which detects force using the resistance change of a piezo-resistor due to deformation, has attracted significant attention. The piezoresistive force sensor has several advantages compared to other types of force sensors, including a high sensitivity, a high spatial resolution, a simple readout circuit, and well-established fabrication techniques. In this type of sensor, piezoresistive silicon elements are typically embedded inside a protective elastic body.
MEMS or microelectromechanical systems use micro-sized components as sensors transducers and actuators. These are currently found in cars, gaming devices, smartphones, and environmental testers. Many of these same MEMS are used in the medical field, for example, the MEMS and neural sensors found in smartphones are also found in pacemakers. Due to the use of this technology in the medical field these systems are commonly known as BioMEMS. Other types use biological components to perform a medical function or application. Applications for these devices exist in diagnostics and therapeutics detection and analysis drug delivery or cell culture. In addition, new emerging markets have made BioMEMS the largest and most diverse application of MEMS devices.
MEMS technology enables a variety of biomedical systems and integrates sensors, actuators, microfluidics, micro-optics, and microscale structural elements with computation, communication, and control for use in medicine to improve human health. With Integrated circuits made using microfabrication techniques, BioMEMS is expected to revolutionize the way medicine is practiced and administered.
Applications of BioMEMS force sensing technique:
Micro-force sensing in ophthalmological surgery:
Scientist used image-guided interventions which using optical coherence tomography to ophthalmic practices. In such applications, sensing the touch/touching force is important to improve performance and ensure safety. Micro scale parts and micro clamps in micro scale assembly processes can be easily damaged by unnecessary forces and therefore force detection is important in these applications.
Micro-force sensing in biological manipulators:
There are many factors that affect the micro grip force, such as contact material type, contact area, and process operating environment, conditions. To achieve better gripping with maintaining the mechanical properties of the material, information about gripping force is important.
MEMS cellular force sensors for biological studies:
MEMS based capacitive force sensors are famous in many biomedical applications to sense/measure microforces and its effect on the functionality of the system. MEMS based capacitive force sensors have already proven themselves in Drosophila flight dynamics, studies, and cell membrane biomechanics applications. Specially, the capacitive MEMS force sensors well suited for these applications due to its high sensitivity, large bandwidth, and large sensing range.
Catheter contact force measurement in Radiofrequency (RF) treatment technique:
Measuring the contact force of the catheter during RF ablation treatment process can reduce the rate of recurrence of AFib (atrial fibrillation). Sensing the contact force helping to have an effective catheter contact force between the catheter and tissue and it able to generate effective power output for Radiofrequency ablation.
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