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High CMRR Instrumentation Amplifier (Schematic and Layout) design for biomedical applications

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Instrumentation amplifiers are intended to be used whenever acquisition of a useful signal is difficult. IA’s must have extremely high input impedances because source impedances may be high and/or unbalanced. bias and offset currents are low and relatively stable so that the source impedance need not be constant. Balanced differential inputs are provided so that the signal source may be referenced to any reasonable level independent of the IA output load reference. Common mode rejection, a measure of input balance, is very high so that noise pickup and ground drops, characteristic of remote sensor applications, are minimized.Care is taken to provide high, well characterized stability of critical parameters under varying conditions, such as changing temperatures and supply voltages. Finally, all components that are critical to the performance of the IA are internal to the device. The precision of an IA is provided at the expense of flexibility. By committing to the one specific task of
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Air Muscle

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Nature can be a great source of inspiration. This Air Muscle is an actuator that works very similarly to a human muscle—it contracts by thickening. Inside the black pouch is a balloon. High pressure air pumped through the tube inflates the balloon causing the muscle to shorten by as much as 40%.
Air Muscles can provide substantial pulling force for their small size; they can exert force 400 times their weight. Typical DC motors or pneumatic actuators can exert about 16 times their weight. The largest of the standard Air Muscles is 11 inches long, weights less than 3 ounces, and can lift 154 pounds!
Air Muscles work when twisted, bent around corners, or under water. It even has a similar power profile to a human muscle: the force exerted decreases as it contracts, just like the strength of your biceps is maximum when your arm is extended and decreases as your arm is bent.


Further Information  
The Air Muscle consists of a rubber tube covered in tough plastic netting which shortens in a scissor action when pulled out like a human muscle when inflated with compressed air at low pressure.
The pull force vs. length diagram is illustrated below. The longer the length, the higher the pull force. However, the strain at high pull force region is much smaller than at lower force region

System Requirements for Air Muscle include: 
  • A source of compressed air, air compressor or hand-pump
  • Piping to deliver this air through the system.
  • Fixtures to terminate air lines on other components of the system, and to each other.
  • Air filtering and regulating equipment.
  • Air flow control equipment (Valves).
  • Muscles
  • Mounting points for the muscles
  • Applications  
    Any place an actuator is needed, such as
    • Robots
    • RC toys
    • Industrial Automation
    • Animatronics/Prosthetics
    Since air muscles have nearly the same power curve and ability as human muscles, they have a great ability to mimic human motion. Other possible applications include blood pressure cuff mechanism, jaws of life, and demolition projects.
  • Common Specifications Weight: 10 ~ 80 g (0.022 ~ 0.18 lb)
    Diameter: 6 ~ 30 mm (0.24 ~ 1.18 in)
    Length (Fully stretched): 150 ~ 300 mm (5.9 ~ 11.8 in)
    Output (Pull force): 30 ~ 350 N (6.6 ~ 77 lbf), normal
    70 ~ 700 N (15 ~ 150 lbf), Max.
    Max. inflated pressure : 2 bar (30 psi), unloaded
    4 bar (60 psi), loaded