2015 International Conference on Communication, Information and Computing Technology (ICCICT), Jan 16-17, Mumbai, India Programmable Chemical Reactions Ninad Dileep Mehendale Snehal Ajit Shah IIT Bombay D J Sanghvi College of Engineering Mumbai, India Mumbai, India Ninad.mehendale@gmail.com snehalshah@gmail.com Abstract— this technical note gives an overview of how a sensors and actuators, a storage and output nodes. Various chemical reaction can be programmed and its need. We also types of valves are used to control the inputs, the multiplexers demonstrate how the device is made with traditional copper clad do the function of controlling the amounts of the inputs which etching. In this paper we mentioned the importance of this have to be reacted to give the output and the rotary mixers are upcoming technology. The methodology used for the fabrication used for the thorough mixing of the inputs in different of one such microchip is unique and low cost. The results obtained after using our programme are matching the traditional proportions. There are two types of storage, the temporary bench top chemical reactions. Our work provides new storage (which acts as a microfluidic storage cell) and the breakthrough to all chemical engineering fields as we require permanent storage (which acts as a reservoir) very less amount of volume as well as time for the reaction. We are using understandable and simple English statements to program the reaction. I. INTRODUCTION A chemical reaction is a process in which two or more chemicals are mixed together in order to form a third product which could be another useful chemical. In majority of the cases the ratio in which the two chemicals are to be mixed is required to be found out. To find this ratio any scientist spends days, or even months. In this processes huge amount of volume of chemical is in turn wasted. Some of the reactions Figure 2: In a traditional lab, large amounts of chemicals have to are exothermic and may cause explosions and potential threat be manually mixed in different combinations to obtain a to the life of the people. Programmable chemical reaction optimised output. The process takes days and even months chips are the systems that process and manipulate small sometimes. Also some chemicals are highly reactive and the exothermic reaction which they undergo may lead to an amounts of fluids using channels with dimensions of tens to explosion. In the programmable chemical chip, a single input can hundreds of micrometers. The chip which we have designed is give multiple outputs within seconds. Also the language used for a version of a lab on a chip device. doing the programming is simple English. There is no danger of any harm or explosions to occur because the amount of chemicals used is very less. (In micro litres) II. THE NEED The development and optimization of many new drug therapies requires long-term local delivery with controlled, but variable dosage. Current methods for chronic drug delivery have limited utility because they either cannot deliver drugs Figure 1: The above chip made of PMMA has two inlets locally to a specific organ or tissue, do not permit changes in and one outlet. The pattern made is a serpentine shaped delivery rate in situ, or cannot be used in clinical trials in an one. untethered, wearable configuration. Pharmaceutical science aims to localize the pharmacological activity of the drug at the Using programmable technology, permutations and a variety site of action. After chemically mixing. The way a of combinations of outputs can be achieved using a single pharmacologically active substance is delivered to the body, input, which in turn optimizes the time consumed doing the has a significant impact on the therapeutic value of manual inspection of the limited number of outputs achieved medication. Targeted chemical mixing systems can directly by using the same input. Such chips are programmed via deliver the payload to the desired site of action without computers. The user has to write a simple code using simple undesired interaction with hazardous chemicals. This is English statements describing the ratio of the chemicals to be especially important for explosive chemicals to avoid side reacted with each other and the time and the output is obtained effects and improve product compliance. The first application automatically. Such a chip normally consists of input nodes, 978-1-4799-5522-0/15/$31.00 ©2015 IEEE 2015 International Conference on Communication, Information and Computing Technology (ICCICT), Jan 16-17, Mumbai, India of programmable chemical reactions has been in the field of • The size of the container is larger than that of the copper analysis. A programmable chemical chip is a device that piece so that the piece is completely submerged. integrates one or several laboratory functions on a single chip. • The FeCl3 solution should be prepared in the ratio of 1gm It is in the size range of only millimetres to a few square of FeCl3 in 500ml of water. centimetres in size. There are many benefits to operating on this scale. Analysis of samples can take place in situ, exactly where the samples are generated, rather than being transported around to a large laboratory facility. The differences in fluid dynamics on a very small scale mean that it is easier to control the movement and interaction of samples, making reactions much more efficient, and reducing chemical waste as shown in Fig.2 III. LITERATURE SURVEY A literature review of articles published between 2008 and 2014 identified a few categories of neighborhood characteristics relevant to what has been discussed in this Figure 3: The above serpentine pattern is first drawn on the Cu technical note. The Shen, Keyue, et al. [1] focus briefly on clad using a nail paint. The clad is then immersed in a FeCl3 manufacturing microchips using different types of foil, any solution where etching takes place. The track width is 200µm and paper having a hydrophobic coating and the surface structure. the height is 35µm and the inlet and outlet holes are 1.5mm Volker et al. [2] focuses on micro chemical reactions. Vaz et al. [3] shows micro droplets are formed in a chemically stable medium on electric panel devices. These devices are substrates which have electrode arrays or electrode dots, and its surfaces are coated by an insulating film (such as Teflon or polypropylene) to prevent discharge and electrolysis of solutions [4]. The Algorithm is quite similar to shah et al. [5] where two inputs are taken and output is fed back to the system. We describe a method to fabricate microchips [6] using a Cu clad on which channels are drawn using nail paints and FeCl3 solution is used for etching. Also a moldable acrylic polymer is used to plasticize the chip. IV.METHODOLOGY The detailed description of the method used to make the chip is as follows: Figure 4: The cu clad with the pattern formed on it is dipped in a On a copper clad piece (copper on one side and plastic on the container which is bigger than its own size. This container other, usually used in making PCB`s), draw patterns using a contains FeCl3 solution. A DC motor is attached to the container. nail paint. This entire pattern consists of inlets, outlets and a The DC motor shakes the container in an up-down motion. This process is carried out at a temperature of 70 degree Celsius for 60 mixing zone. The following diagram depicts the pattern with seconds. Once the cu clad is removed from the container, masters dimensions. The track width is 200µm and the height is 35µm are formed on the CU clad. and the inlet and outlet holes are 1.5mm Once the solution is prepared, dip the copper piece in the Using the dimensions of the channel and the flow rates of the container. To the container is attached a DC motor which fluids, we can calculate the Reynolds’s number which turns shakes the container in clockwise and anti-clockwise direction out to be very low (>>1) at 10 degrees (it is basically an up-down motion) The copper piece is shaken in this container at 70 degree Celsius for Re= …………………………….. (1) approximately 60 seconds. Etching takes place and masters are formed on the Cu clad Where V = flow velocity, L = channel diameter, µ = viscosity piece. This process does not remove all of the copper from the of fluid, ρ = density of fluid plate. Instead channels of copper are formed approximately 10 to 12 microns in size. The height of the channel formed varies Once the patterning with the nail paint is done on the Cu clad with the FeCl3 solution concentration. But normally a height piece, it is dipped in a container which contains FeCl3 ranging from 10 to 20 microns is normally achieved. Using a solution. The following points should be noted while doing the normal scrubber, all the nail paint is scrubbed off the copper above step. clad piece. Hence, the pattern which is required gets transferred on the copper clad piece. 978-1-4799-5522-0/15/$31.00 ©2015 IEEE 2015 International Conference on Communication, Information and Computing Technology (ICCICT), Jan 16-17, Mumbai, India called Tygon tubing. These tubes are then attached to two 5 ml syringes from where the chemicals can be loaded in the chip. The top of the syringe is fit on to a fixed assembly and the end is controlled by either a DC motor or a servo motor. Depending on the accuracy we desire, we choose from the above two choices. • DC motor controlled mechanism • Servo motor controlled mechanism The DC motor connected to the syringe is connected to a current driver IC (ULN 2003). This IC is connected to an AT Mega 8 microcontroller. A keypad is connected to take inputs from the user and to see the inputs a LCD is connected. The . rotational motion of the DC motor is converted into linear Figure 5: once the Cu clad removed from the solution, not all of motion thus moving the syringe back and forth, thus the Cu gets etched. Instead, channels of 25µm in height are controlling the flow of the chemicals. formed. With the help of a scrubber, the remaining nail paint is removed ASTRON-R which is the commercial name of a poly (methyl methacrylate) is available in the form of a powder and a liquid. It is a mouldable acrylic. The powder is first evenly spread on our piece. On it is evenly spread, the liquid. The powder and liquid mix with each other and within approximately 5 minutes plasticize and our chip is ready. If we want the base to be visible, then we can use a glass cover slip at the base which is of the dimensions 24mm*60mm. To make the chip completely transparent, sandwich it between the gaps of two glass coverslips creating a channel between them. Once the chip is ready, we connect the tubing and connectors to it. Figure 7: Servo motor controlled mechanism: The inlets of the chip are connected to 2 syringes by means of tygon tubes from where the chemicals can be loaded into the chip. The ends of these syringes are connected to Servo Motors. The Motors are connected to an AT Mega 8 microcontroller. A keypad is connected to take inputs from the user and to see the inputs a LCD is connected. The angular motion of the Servo motor is converted into linear motion thus moving the syringe back and forth, thus controlling the flow of the chemicals The connections are the same as that of the DC motor. It just does not include the water driven IC. The servo motor is directly connected to the microcontroller. V. EXAMPLE Suppose we want to see the output of the following two Figure 6: DC motor driven mechanism: The inlets of the chip are inputs: Chemical A: 40ml, Chemical B: 20ml and Total of connected to 2 syringes by means of tygon tubes from where the chemical A&B: 60ml chemicals can be loaded into the chip. The ends of these syringes Here, as we can see the total of both the chemicals is not 100. are connected to DC Motors. The Motors are connected current Therefore the microcontroller will calculate the percentage of driver IC (ULN 2003). This IC is connected to an AT Mega 8 microcontroller. A keypad is connected to take inputs from the the chemicals. user and to see the inputs a LCD is connected. The rotational motion of the DC motor is converted into linear motion thus %Chemical A= 40/60 *100 = 66.67% moving the syringe back and forth, thus controlling the flow of %Chemical B= 20/60*100 = 33.33% the chemicals. This percentage of the chemicals is mapped to the angle of the The connectors which are used are 1.5mm and are servo motor. So if 100% is equivalent to 180 degrees of the manufactured by Cole-Parmer and the tubing which is used is servo motor, then accordingly, motor 1 which controls the 978-1-4799-5522-0/15/$31.00 ©2015 IEEE 2015 International Conference on Communication, Information and Computing Technology (ICCICT), Jan 16-17, Mumbai, India flow of chemical A will move at an angle of 135 degrees and motor B will move at an angle of 45 degrees. In case of the DC motor driven mechanism, the percentage of chemicals is directly proportional to the time for which the motor runs. Therefore DC motor 1 will run for 66.67 seconds and DC motor 2 for 33.33 seconds. VI. RESULTS Using the dimensions of the channel, the volume of the channel can be computed. There are various mixing designs available. The diffusion time is directly proportional to the length of the channel. The longer the length of the channel, the more will be the diffusion time and hence more diffusion will be obtained. The DC motor operated mechanism is better for handling 5ml syringes. However, the servo motor gives more accurate results. VII.CONCLUSION Programmable chemical reaction is an up and coming technology. New breakthroughs are made in this particular region almost every day. However it will still take some time for it to become a mainstream technology. The chip that we fabricated has many advantages. It saves a lot of time, even if the reaction which we perform is explosive, the damage done will be next to nothing and there are no chances of any physical damage. The quantity of chemicals used is in the range of Nano and Pico liters so there is minimal wastage. Also the energy consumption is also very less. ACKNOWLEDGMENT Authors would like to thank Dr. Debjani Paul, Dr. V. Ramesh, for the valuable guidance. We would also like to thank our friends Dr. Madhura Mehendale, Tanveer Dapherdar, Meenakshi Singh, Prasad, Samrat, Sampath, Amar, Akshi for encouragement and all the members of IITB and D.J.Sanghvi College of engineering for their support and infrastructure. REFERENCES [1] Shen, Keyue, et al. "A microchip-based PCR device using flexible printed circuit technology." Sensors and Actuators B: Chemical 105.2 (2005): 251- 258. [2] Hessel, Volker, Steffen Hardt, and Holger Löwe. Chemical micro process engineering: fundamentals, modelling and reactions. John Wiley & Sons, 2006. [3] Vaz, Nuno A., George W. Smith, and G. Paul Montgomery Jr. "A light control film composed of liquid crystal droplets dispersed in a UV-curable polymer."Molecular Crystals and Liquid Crystals 146.1 (1987): 1-15. [4] Yan, Zong Cheng, Chen Li, and Wang Hong Lin. "Hydrogen generation by glow discharge plasma electrolysis of methanol solutions." International Journal of Hydrogen Energy 34.1 (2009): 48-55. [5] Shah, Ankit, and Ninad Mehendale. "Decrypted Stegnography." International Journal of Scientific & Engineering Research, 4.7 (2013): 1154- 1156 978-1-4799-5522-0/15/$31.00 ©2015 IEEE
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