CENTRIFUGE WITH ADJUSTABLE SPEED AND DIRECTION OF ROTATION BY: AARTI SHINDE JYOTI SHUKLA MANISH PILLAI SARANYA NAIR

INTRODUCTION A centrifuge is a piece of equipment, generally driven by a motor, that puts an object in rotation around a fixed axis, applying force perpendicular to the axis.

PHYSIOLOGICAL BACKGROUND Early instruments were hand powered, but in 1912, with the introduction of electric centrifuges, that changed. The early centrifuges were mostly used for non-biological applications, such as separating milk and collecting precipitates.

PRINCIPLES OF CENTRIFUGE The centrifuge works using the sedimentation principle, where the centrifugal force is used to separate substances of greater and less density. Basis of separation: Size Shape Density

CENTRIFUGAL FORCE Let us consider a body of mass m rotating in a circular path of radius r at a velocity v. The force acting on the body in a radial direction is given by: F = The same body experiencing gravitational force. This can be expressed as, G = mg

CONTINUED... The centrifugal effect is the ratio of the two forces, so that: C = F / G = mv2 / mgr = v2 / gr But v = 2πrn So, F / G = (2πrn)2 / gr = 4π2r2n2 / gr = 2 π2n2d / g ------------------------ (1) g = 9.807 Centrifugal effect = 2.013 n2d Provided that n is expressed in s-1 and d is in meter.

METHODOLOGY In process Suspension Separation complete Induced gravitational field Supernatant Precipitate In process Suspension Separation complete Pellet Supernatant Relative centrifugal force or Centrifugal effect

TYPES OF ROTORS Fixed Angle Rotor

Swinging Bucket Rotor

BLOCK DIAGRAM LCD DISPLAY ATMEGA 8 KEYPAD POWER SUPPLY MOTOR DRIVER TEST TUBES

ATmega8-Microcontroller

MEMBRANE KEYPAD

VOLTAGE REGULATOR

L293D

DC MOTOR

DC MOTOR

LCD

CRYSTAL

10 K RESISTOR

100 microfarad CAPACITOR

Bug strip Male Bug strip Female

CIRCUIT DIAGRAM

APPLICATIONS OF CENTRIFUGE Production of bulk drugs Production of biological products Biopharmaceutical analysis of drugs Evaluation of suspension and emulsion Blood plasma is separated from whole blood Different particle size fractions are separated by using control of speed of rotation and rate of flow

ADVANTAGES Faster and reliable Several specimens can be centrifuged at ago e.g. blood &urine Not tiresome as compared to manual centrifuge machine Safe once the specimen are enclosed into the machine  

DISADVANTAGES Time wasting to the patient Exhausting of the laboratory technician Specimens may spill out of the test tubes The capacity is limited.

CONCLUSION Thus, we can see that the centrifuge machine is an essential medical device for every biological and clinical laboratory as well as medical practice. The centrifuge may seem a rather common machine, but newer models have become more complex, as higher speeds have become necessary for certain processes and applications and as more precise controls are needed.

BIBLIOGRAPHY Basic medical laboratory techniques - Page 69 by Barbara H. Estridge, Anna P. Reynolds, Norma J. Walters Fundamentals Of Bioanalytical Techniques And Instrumentation - Page 118 by Ghosal & Srivastava Basic Clinical Laboratory Techniques - Page 85 by Barbara H. Estridge, Anna P. Reynolds

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