shashanka doddamani you can find about DNAmp here

DNAmp

India's First Natively Designed and Developed PCR Machine

Product Development-

Bhat Biotech India (P) Ltd, Bangalore

http://www.bhatbiotechindia.com/pcr.html

The Problem Statement

Bhat Biotech India is pioneering the manufacturing of the Polymerase Chain Reaction (PCR) machine in India. I was offered a role in its development with the task of developing and coding an effective PID control algorithm for the Thermal Control Module (TCM) of the machine, that uses a solid state Peltier Thermo Electric Cooler (TEC). I also took the initiative to work on the testing and quality control as well as the brand of the product.

Tools and Hardware Used

Electronics Design

Software: Software:

MPLAB IDE - PID Coding GDDX, VGDD -TouchScreen UI Developed

Docklight - Serial Port Communications AutoCAD 2012 (2D and 3D modelling)

Graph - Math plots

Hardware: Hardware:

Microchip Digital Signal Controller Silicon Rubber

Thermal Control Module (TCM): Particle Board (Prototyping)

Peltier TEC Stainless Steel sheet (Manufacturing)

NTC Thermistor

LM 35 Temp Sensor

Wheat Stone Bridge

4.3' TFT LCD Graphic touchscreen

Fluke CNX t3000 Thermometer

About the project

After graduation I got acquainted with Dr Shama Bhat, a former professor of the University of Pennsylvania, Indian Institute of Science and a successful entrepreneur who now heads Bhat Biotech India Pvt Ltd., a company specializing in biotech diagnostic kits and test devices. He had a look at my work and offered be a Research Assistant position in his R&D Lab, where he gave me a tour and expressed his ambition to diversify into Biotech Electronic Instruments such as the Polymerase Chain Reaction (PCR) machine. I saw it as an opportunity to leverage my learning to help design a new product for the Indian market that would be disruptive through its low cost. Though it sounded simple, there were formidable challenges such as robust control of the thermal control module of the machine.

I was excited about the idea, and found it to be full of challenges. The team was a small one, working on diverse aspects of the machine for the past 1.5 years.They had been working extensively on the dsPIC30 Digital Signal Controller which controlled the operation of the thermal cycler. The TEC was operated through PWM by the Controller, an LCD keypad interfaced had been developed and a high current H bridge was built by them to control the TEC's polarity for heating/cooling.

Robust Control of TEC

I stepd in and learned about circuits and theory of the control of temperature using PID control algorithm. I realized that for every range of set points, a unique set of PID constants did the job of establishing adequate control. A discrete plot of tabulated PID constants as a function of the set point was nonlinear as expected. I used polynomial regression to interpolate and extrapolate the discrete behavior to get a continuous curve for the entire set point range of 4-99 degrees Celsius. The equations were fed into the algorithm to compute PID constants as a function of the set point.

Since performance also depends on the ambient temperature, the relative set point was computed using an additional ambient temperature feedback, which was now used to compute the PID constants. This made the algorithm work seamlessly in a variety of thermal environments with overshoot/steady state error within +/-0.1 degrees Celsius.

Research Paper

We documented the study, algorithm and results as a research paper titled 'A simple and intelligent nonlinear PID temperature control with ambient temperature feedback for nonlinear systems'. The paper was presented at the IEEE International Conference on Circuits, Control and Communication (Ccube 2013) on December 27-28 at RNSIT, Bangalore. It is now indexed in IEEE Xpolre.

Testing and Modifications

Since there was no Quality control and testing personnel, I performed all the rigorous test procedures, detecting flaws and suggesting necessary modifications. I worked with other departments and Biotechnology professionals to know their requirements and compared our machine to arrive at important functionality and design modifications.

Some of the Major Modifications I suggested and worked to implement them were as follows:

Dimensions selected by them for the well (well is the one which heats and cools the PCR sample tubes) gave unsatisfactory results, Hence I thoroughly inspected the issue and selected the suitable dimensions for the well which gave wonderful results. This became a standard for Bhat Biotech's future PCR instruments.

Added an extra functionality to the PCR machine to store the sample at 4 Degree Celsius for an infinite time after the PCR
I have used Fluke CNX t3000 to calibrate the temperature of the PCR machine to the exact set temperature with a margin of +/-0.1 degrees Celsius
There was a condensation of water in the well when the PCR machine runs below room temperature. This was a serious problem. I added silicon rubber gasket to attain an air tight zone around the well to avoid water condensation. I submitted a report and implemented it in one of the machines, result was great, and everyone was shocked to see literally no condensation of water on the well. Rubber gasket is being implemented in every machine manufactured and this became one of the notable features of our machine.

Other Responsibilities

I have involved myself in the field testing and Marketing of the PCR Instrument, and worked for the generation of User manual, Product documentation and Reports, I have also worked with different collaborating institutions/Hospitals to validate and promote the instrument.

Results

I learnt a lot about nonlinear control and PID, developed an algorithm that controls the temperature to an accuracy of +/- 0.1 degrees Centigrade. I observed and learnded the entire process involved in the product development

The support and encouragement I received at the workplace resulted in the effective completion of my work and making the DNAmp market ready at an affordable price.