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BME 352 - Biomedical Engineering Design and Manufacturing II

Final Deliverable Project Rev: A - Printed 4/1/2015 1 Confidential & Privileged: This document contains confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited

Title: Final Deliverable - Reverse Engineering Team 4 for LifeStraw

Instructor Signatures

UNC/NCSU BME Date:

Andrew DiMeo, Instructor

UNC/NCSU BME Date:

Michael Browne, TA

Student Signatures

NCSU BME Date:

NCSU BME Date:

NCSU BME Date:

NCSU BME Date:

NCSU BME Date:



Table of Contents 1. Phase 1: Initial Research 3 At a Glance 3 History 4 Applications 4 Device Specifications 5 Filtration 5 Competition 7 Limitations 8 Flow Counters 8 2. Phase 2: Black Box Reverse Engineering 9 Input 9 Output 10 Black Box Q&A 11 3. Phase 3: White Box Reverse Engineering 13 Non-Destructive Disassembly 13 Destructive Disassembly 14 Comprehensive Bill-of-Materials 17 4. Phase 4: New Features and Models 17 Limitations & Use 17 New Improvements 17 SolidWorks Models 19 5. Bibliography 21 6. Appendix 22 SolidWorks Drawings Unmodified LifeStraw Drawing 22 Flow Meter LifeStraw Drawing 23 Flow Meter and Turbine Drawing 24 Flow Meter Adapter Drawing 25 Disinfectant Bottle Drawing 26 Disinfectant Bottle Holder Drawing 27 Disinfectant Bottle Holder Strap Drawing 28 Disinfectant Module LifeStraw Improvement 29



Phase 1: Initial Research At a Glance Device, model number, serial number, and manufacturer: Vestergaard’s LifeStraw device (model number 085787-CHE-001) What is the concise physical description? From what materials is it made? The LifeStraw is a cylindrical tube made from lightweight durable plastic it is 22.5 cm long and 2.5 cm in diameter with a dry weight of 56 grams. It operates via mechanical filtration. Hollow fibers trap bacteria, and pathogens while filtered water flows through. What are its primary function/s? The LifeStraw is a point of use filter designed to decontaminate small volumes of drinking water (approximately 2L per day). The device is designed to remove 99.9999 percent of bacteria and 99.9 percent of protozoan parasites, while reducing the turbidity of the water. What are the clinical applications of the device? As of 2012, 748 million people worldwide relied on unimproved drinking water sources. This puts these people at significant risk for developing water related infectious diseases including diarrheal disease. In fact, 4 billion cases of diarrhea occur annually, and 88% of these cases are directly attributed to inadequate drinking water sources. How is it powered? User-generated suction at the mouthpiece powers the LifeStraw filtering device. Who is the intended final user (describe the intended target market)? While the device was designed as a solution following large-scale natural disasters, LifeStraw technology has been used in developing countries where people continuously lack access to a clean water supply, and for hikers. How will it assist the final user? The LifeStraw serves as a point of use water filtering device, which will provide clean drinking water to its user. If used properly, it is designed to filter at least 1000 Liters of water at a rate of 2 Liters per day (designed to provide clean drinking water for one person for a full year). In what environments will it be used? The LifeStraw should be used on freshwater supplies.



Will it function without all (or some) of the inputs? The LifeStraw requires its user to apply suction at the mouthpiece, and requires a water supply at the inlet. The device will not work without these two inputs. Are there any self-tests? No, under the current conditions, the LifeStraw is a very simple design, yet does not include any self-tests. Possible improvements could involve self-tests, which ensure that the water being produced meets the filtering standard or a flow counting device. History On December 26, 2004, a massive tsunami devastated coastal areas of 11 countries around the Indian Ocean [5]. The event killed more than 280,000 people, and more than one million survivors were severely affected by the disaster [5]. The tsunami severely impacted drinking water supplies, damaging piped in water supplies and ground water pumps, and introducing salt water to previously freshwater wells and surface sources. In addition, due to issues with wastewater treatment following the disaster, survivors were placed at an increased risk for waterborne diseases such as diarrhea, cholera, typhoid and hepatitis. For the first 48 hours, survivors were forced to rely mainly on unaffected surface sources, and some bottled water, however these sources were limited and many of the survivors had little water directly following the event [5]. This water shortage prompted efforts by Vestergaard, a company focused on world health and sustainability. In 1999, Vestergaard had partnered with the Carter Center to develop a straw device, which would filter drinking water to protect people from guinea worm larvae in their water supply [4]. However, following the tsunami in 2005, the company sought to expand the implications of this device by creating a straw, which would also remove bacteria, protozoan parasites, and particulate matter. This resulted in the development of the LifeStraw in 2005, which has now been implemented as a solution for water shortages following natural disasters such as the Haiti earthquake and Pakistan floods [8]. Applications In addition to its uses in natural disasters, LifeStraw technology has been implemented for many people living in developing countries who lack access to an adequate water supply. According to a survey by the World Health organization, approximately 78 million people worldwide lack access to clean safe drinking water each day [7]. This lack of clean drinking water puts these people at a great risk to contracting many infectious diseases, including diarrheal infections. In fact, of the 4 billion cases of diarrhea reported annually, 88% of them can be directly attributed to a lack of clean drinking water [7]. LifeStraw technology is a low cost, individualized water treatment method, which has the potential to significantly reduce the spread of waterborne diseases worldwide. Due to the LifeStraw’s ability to make a huge impact on the lives of people in developing countries, Vestergaard has made a deal that for every LifeStraw purchased; an additional straw will be given to a person in a developing country who lacks access to clean drinking water [4]. Many hikers have also used the LifeStraw technology



to safely drink freshwater from a mountain stream or lake rather than having to carry their own water supply on extended hiking trips. Device Specifications Vestergaard’s LifeStraw (model number 085787-CHE-001) is a point of use water filtration device [6]. The LifeStraw is a cylindrical tube made from durable plastic, which is very lightweight, only weighing 56 grams [4]. Users place the filter end of the tube in a water supply, and apply suction to the mouthpiece end of the tube in order to acquire water. After the user has finished drinking, the user must blow out through the mouthpiece, removing excess water from the filter. When used properly, one LifeStraw can be expected to purify a minimum of 1000 liters of water at a rate of 2 liters per day [8]. Based off these specifications, the device is expected to provide filtered water for one person for one year. Filtration The LifeStraw filtration device is designed to remove 99.9999 percent of bacteria and 99.9 percent of protozoan parasites from water sources [6]. The filter also reduces the turbidity of the water by filtering out particulate matter, which is larger than .2 microns [6]. In 2011, the World Health Organization determined specifications for health-based evaluations of drinking water filtration [1]. These specifications outlined a tiered system by which the World Health Organization can judge the quality of a filtration device. Based on a filtration device’s ability to remove viruses, bacteria and protozoa from a water source, the World Health Organization assigns a score of “interim”, “protective”, or “highly protective” [1]. Previous analyses of the LifeStraw device have determined that the device exceeded the World Health Organization’s requirements for a highly protective water treatment device. Table 1 shows the results of a study by the University of Arizona, in which the LifeStraw exceeded filtration expectations for a highly protective filtering device in bacterial, viral and protozoan removal [5].



Table 1. Removal of Test Organisms by LifeStraw Units [2,3]

Liters filtered Log10 Removal of Indicated Organism

E. coli MS-2 virus Rotavirus SA-11 Cryptospordi um parvum

0 >6.53 >5.26 >5.11 >4.16

200 >6.40 >5.41 >5.10 >4.11

450 >6.70 >5.52 >5.10 >4.01

900 >6.81 >5.51 >5.10 >4.19

EPA Standard: “Highly Protective”

>6.00 >5.00 >5.00 >4.00

The original LifeStraw design used chemical filtration, consisting of a plastic mesh and polyester mesh screen, a halogenated ion exchange resin, and a silver impregnated granular activated carbon block. However, this chemically based filtration system limited the applications of the device, confining filtration to only water within a small range of water temperatures and pH values, due to risk of iodine exposure or poor water purification in water samples which deviated from a normal range [8]. As a result, the device was redeveloped in 2014 to be an entirely mechanical filter design, which does not have as many limitations [3].

Figure 1. LifeStraw Design. The LifeStraw consists of a mouthpiece (1,2), connected to a rigid



hollow plastic tube (3) via a seal (4). Within the plastic tubing, there is a supporting structure (5), which serves as a seal to the inner walls (6) of the tubing. Many hollow fibers (10) are connected to the support member and extend into the hollow compartment towards the mouthpiece [3]. Water first enters the LifeStraw via the filters (shown as 14, 15 in Figure 1). Initially, the hollow fibers (10 in Figure 1) are filled with air, allowing air to escape through the membrane walls and water to flow into the inner channel of the fibers. A mesh filter (shown as 16 in Figure 1) prevents large particles from entering into the water supply, while a textile filter (14 in Figure 1) removes other smaller microbes and microparticles. Water is then filtered via an inside out motion throughout the hollow fiber membranes. In this case, cleaned water can leave the membrane and flow out into the inner plastic compartment towards the mouthpiece, while bacteria and other microbes remain inside the hollow fibers [3]. Competition While the LifeStraw device is a useful point-of-use water treatment method, there are several other methods commonly used for water treatment, including boiling, solar disinfection, chlorination, filtration, and Ultraviolet radiation [8]. Boiling water is one of the best-known methods of water treatment. This method is effective at de-activating viral, parasitic, and bacterial pathogens, and is a relatively simple process. However, process of boiling is often economically and environmentally unsustainable, provides no residual protection, and presents a significant risk for scalding users, especially infants [8]. Solar disinfection uses a combination of ultraviolet radiation from the sun, and heat to treat water. While the method is simple and inexpensive, it is ineffective with turbid water, and is not practical with large volumes of water [8]. Chlorination uses sodium hypochlorite as a chemical disinfectant. While sodium hypochlorite is safe, effective, relatively inexpensive, and can be produced on site, it is ineffective against parasites and viruses [8]. There are many types of filters used for water treatment including granular media filters which use bio-sand, vegetable and animal derived depth filters, membrane filters composed of paper, cloth, or plastic, porous cast filters from ceramic pots, and septum and body feed filters. However, filtration alone has been proven ineffective at reducing viruses and bacteria in water at a household level [8]. Ultraviolet radiation is often combined with a coagulation/flocculation treatment or filtration system to reduce the turbidity in the water. This combined system works very well at removing all waterborne pathogens, and does not affect the odor or taste of the water. However, the system does require energy input from electricity or a battery supply, which may not always be available in developing countries [8]. The LifeStraw device is very different from most of these traditional methods, in that it is individualized and does not require infrastructure such as electricity, or large basins and equipment in order to operate. As a result, this device is portable and easy to use, even for children. However, where as many of the



traditional methods can provide clean water to a large population, or allow clean water be stored for long term, Lifestraw technology is limited to small volumes of water and restricted to point of use methods. In addition, the LifeStraw design prevents the cleaned water from being used for other applications such as wound care, bathing, or cooking. Limitations Although LifeStraw technology is effective as an individualized water treatment option, it does have some limitations. Some of these limitations can be associated with the input water requirements. For instance, the LifeStraw filter technology is unable to remove salt from the water, and thus the straw is ineffective on cleaning seawater or brackish water [6]. This may prohibit people who live near the ocean from using the device. In addition, the device is unable to remove hazardous pollutants such as heavy metals and industrial chemicals from the water, and thus, LifeStraw advises that the device should also not be used downstream of an industrial factory [6]. Additional risks are associated with the water temperature and pH. Due to the threat of issues with excess iodine from the resin chamber, the water temperature must not exceed 77 degrees Fahrenheit [6]. In addition, the pH of the water must be around the normal range in order to maintain the optimal amount of iodine entering into the water [4]. One common issue associated with the LifeStraw device is that the mouthpiece is prone to getting contaminated by bacteria, or viruses, which would lead to issues with the effectivity of the device. In essence, the filtered water which should enter the user’s mouth as clean water following the three step water treatment process inside the straw will interact with a contaminated mouthpiece, and thus, the user gets a tainted supply of water [5]. This is a greater risk for people in developing countries who often try to share LifeStraw devices between different users due to the sheer cost of the device. While the company clearly states that the straw is intended to only be used with one person, many people do share these devices, and thus, further developments improving the sanitization of the mouthpiece may be beneficial for future analysis. Flow Counters Although the LifeStraw system is designed to last for 1000 Liters of water consumption at a rate of approximately 2 liters per day, the device does not alert users of when they are getting close to the 1000 Liter capacity. Therefore, a potential improvement for this system would be to include a flowmeter, which would allow users to know how many liters of water the straw has filtered. Most flowmeters use one of two techniques to determine the flow rate of a fluid: pressure difference, or the rotation of a turbine. Pressure centered flowmeters, such as the Pitot tube; utilize the principles of Bernoulli’s equation. In this case, a tube is connected to the pipe to which the flow rate is desired. The attached tube rises up perpendicular from the pipe, and splits in two directions towards the top of the tube. The tube measures the static pressure of the pipe, or the pressure the water is under at that point, but also the stagnation pressure, a value calculated by the height water will rise in a tube based on its velocity and the pressure



the fluid is over. By computing the difference in these values, the flowmeter can calculate the velocity of the fluid. In contrast, many inline flowmeters rely on the rotation of a turbine. In this case, a windmill type turbine is placed inside the line of flow. As water flows through the tube, the turbine rotates at a rate, which is proportional to the velocity of the fluid. A sensor measures the rate of turbine rotation, and computes the flowrate of the fluid and the cumulative amount of fluid, which passes through the tube. Both types of flowmeters have strengths and weaknesses for being applied to the LifeStraw device. For instance, since many Pitot tube meters function without any electronic sensors, this option would allow the LifeStraw to remain free of electronics. However, this design requires that an additional tube be added to the side of the device, which could interfere with use, and would certainly affect the size and weight of the device. The biggest drawback is based on the fact that this device can compute the velocity of the fluid, so a stopwatch would have to be used to determine the amount of fluid consumed. As a result, an inline flowmeter would likely be the best option for this device, as it can not only compute the flow rate, but also the amount of fluid passing through the tube. However, this type of device requires battery power, which would minimize its utility in the developing world. Further investigation of these devices and an assessment of the intentions of the LifeStraw are necessary prior to implementing a flow counter design. Phase 2: Black Box Reverse Engineering Input: Water was taken from a small pond located along Wolf Village Way at Wolf Village Apartments. The pond was brownish green in color, filled with algae, geese and other organisms, and likely runoff from surrounding roads and parking lots. 2(a). Input of dirty pond water.



2(b) Local pond at Wolf Village. The pond is surrounded by streets contributing to runoff, geese, amphibians and other organisms. The pond is a greenish brown color and does not appear to be clean, nor would it be recommended that anyone drink straight from the pond out of thirst without first filtering the water.

Figure 2a-b: Input (a) collected from a pond (b). (3) Output: The water came out of the straw clear and appeared to be clean. The taste was not comparable to that of clean water, and still tasted relatively dirty. The users had no other way of testing the cleanliness of the sample within the time span of the project.

Figure 3: Output of supposed clean water.



The overall cleanliness of the water appeared to improve drastically based on the visual quality of the input compared to the output.

Figure 4: Visual comparison of input (left) v. output (right). Black Box Q&A How is it powered On and Off? The LifeStraw is operated through manual power from the user. The user must suck water up through the straw in order to mechanically filter the water. When sucking water through, the first few seconds of sucking are more difficult for the user, however once the water has successfully been filtered through the barriers, it becomes easier to pull the water up through the device. After using the device, it must be cleared of water by blowing into the straw. Any remaining water in the device will trickle out when the user pushes air out. How are the functions accessed? Because of time limitations for the project, users determined the cleanliness of the water based on taste and texture. The taste of the water was compared to that of fresh, clean, pre-filtered water. The texture was noted by acknowledging any particles or grit in the output. No group members reported any side effects after drinking the pond water through the straw.



What are the physical inputs? Dirty water was taken from a local pond by Wolf Village containing runoff, feces, animals, organisms, and algae. The user was then required to suck through the straw to test the function. What are the ranges of the inputs? Though the specific input used for testing was from a pond, any type of water may be filtered using the device, excluding seawater. What information does the user receive? The user receives the filtered water (output) directly by mouth. The quality is then judged by taste and texture of the water. What is the logic with the human interface? Drinking through a straw is a common way of consuming liquids, though it is unnatural to drink directly from a dirty source.



Phase 3: White Box Reverse Engineering Non-Destructive Disassembly:

What tools are required for disassembly & assembly? Any special tools required? No special tools were required for reversible disassembly. The pieces could be taken apart by hand, though the mouthpiece and filter cap required some extra force to pull off. Any special notes that would make the process easier next time? Taking the mouth cap off took a few minutes because it was initially attempted to pull the ring holding it on off the top. The two plastic rings where the handle hooked were in the way so it was discovered that pulling the ring down the tube and off the bottom was easier. What is the preferred sequence for assembly & disassembly? The preferred sequence for assembly would be mouthpiece cap, filter cap, and then string handle. The preferred sequence for disassembly would be string handle, filter cap, and then mouthpiece cap. How many individual components can you reversibly disassemble the unit into without cutting, melting or breaking anything? There are four individual components.



Destructive Disassembly:

Figure 6 Parts list: a.) Handle b.) Main filter fiber bundle c.) Plastic netting covering filter (pulled back for better view) d.) Mouthpiece cap e.) Bottom filter cap f.) Thin plastic ring g.) Main tube body (cut in half) h.) Sliced off bottom part with thick clear plastic Disassembly Tools Used:

- Multi-Pro Dremel 5000-35000 RPM Model 395 - Wiss Drop-Forged Tin Snips - Pliers



- Flashlight - Hand saw - Table-mounted clamp

What are the major components of the device internally? The major component is a bundle of long, very thin, hollow fibers, surrounded by elastic polymer netting and fused to the bottom by a clear, hard plastic. There is also a thin, plastic ring that holds the bundle and netting tight together. What specific sensors collect the inputs? Inputs are collected by the fibers of the main filter after passing through the dark blue filter on the bottom. An example input would be bacteria-infected pond water. What are the scientific principles of how the sensors function? The only real sensor is the filter. The filter consists of a bundle of micro-porous hollow fibers bent in half so that all of the openings face downward and water can be sucked in. An application of pressure at the mouthpiece area, usually by a person sucking air in, contaminated water in drawn up into the fibers. Nothing more than 0.2 μm can be pulled up into the straw. The fibers then mechanically filter out 99% of bacteria and 99% of protozoa, letting only the water seep out into to the main tube. The person drinking out of the straw can then consume this filtered water. After drinking the water, the user is to blow outward through the straw to expel the material trapped in the filter. [4] Why are these sensors used? The filter is mechanical, not chemical so that there is no leaking of chemicals into the filtered water. The older versions of LifeStraw used layers of chemical filters, but the new design does not for that reason. How are the inputs processed? Inputs are processed by size and shape of particle. If it is greater than 0.2 μm, it can’t enter the straw, and then if it is bigger than a molecule of water, or too irregularly shaped, it can’t leave the filter. How are the outputs processed? The output aren’t processed by the device itself, but can be processed by the user tasting clean water. How are the outputs translated to human senses? The output is filtered water that is directly tasted as the user drinks through the device. The quality of the output can be determined mostly by seeing whether or not people who drink water filtered by the LifeStraw get bacterial infections. The taste of the water could also be an indicator



What is the logic of the workings of the inter-related components? Starting at the bottom of the LifeStraw, the bottom filter, made of the dark blue plastic, covers the area where the main filter’s openings are and keeps very large particles from clogging up the straw. The thick plastic holds the openings of the filter fibers in place just above the bottom. This keeps them in place and facing downward. The netting surrounding the filter, is attached to the clear plastic right at its top edge, since it does not need to reach the bottom, it just needs to be held in place. Just above where the thick plastic starts, there is a thin plastic ring to hold the netting and filter together, so as not to let them spread out too much lower in the tube, and leak out water. The netting and filter reach the length of the tube so as to provide the most area for filtering to occur. What are the standard components? Filter cap, main tube, mouthpiece cap, and main filter What are the subassemblies? The main filter is a subassembly of a bundle of hollow fibers, surrounded by slightly elastic netting, held tight by a plastic ring, and fused to the main body by a clear plastic at the bottom that also holds its openings facing downward. What are the specialized components? The entire device is made of specialized components. None of it is generic or made for any other application. What materials constitute the subassemblies? All of the subassemblies are made of specialized plastics for the LifeStraw, so exact information was difficult to find. How are the subassemblies fabricated? The fabrication of the subassemblies is difficult to determine without manufacturer contact, but it can be theorized that the fibers were fabricated as one long fiber, and cut at regular intervals to make a mass of fibers of the same length. The netting was most likely placed around the filter, and both were pushed into the clear plastic while it was still hot and viscous. The assembly was allowed to cool slightly, and then the bottom was sliced off so that the openings of the fibers would not be covered by the plastic. Then the plastic/filter was slid into the light blue tube from the bottom and the dark blue bottom part was placed below it. How are the various subassemblies fastened and connected? The subassembly of the filter is attached to the rest of the device via fusion with the clear plastic piece inside the bottom of the device.



Comprehensive Bill-of-Materials

- Mouthpiece cover - Bottom filter cover - Detachable string handle with plastic clamps - Outer body (including mouthpiece, bottom dark blue filter - Main filter fiber bundle - Thin plastic ring - Thick, clear plastic filling

Phase 4: New Features and Models Limitations and Use What are the limitations of the device? The LifeStraw’s primary limitation is any point on the device that the user interacts with where there is potential to compromise the sterility of the device. As such, the mouthpiece is this device’s main limitation. Consider the LifeStraw’s applications in developing countries or disaster scenarios where the device may be shared between multiple users. Although the liquid coming out of the device may be safe to drink, the bacteria/pathogens from one user’s saliva may contaminate the mouthpiece and spread to subsequent users. This undermines the fundamental purpose of the LifeStraw. Who is the device intended to be used by? This device is intended to be used by users in developing countries where clean drinking water is scarce. Additionally, this applies to disaster-related scenarios where clean drinking water may not be immediately available. Lastly, this device is intended to be used by recreationalists (hikers, campers) both as a primary method to acquire water and as an emergency method as well. New Improvements What improvements can be made? There are two main improvements for this device that can be made. First, it may be necessary in some situations to track the amount of water that has been processed through the LifeStraw. This may be to measure the life of the filter in heavy use situations (developing countries & disaster scenarios) or for a hiker looking to make sure he/she has consumed an adequate amount of water in a day. An integrated flowmeter would solve these problems by providing valuable information to the user or organization. This improvement should be low-cost and durable and preferably attach to an existent LifeStraw (i.e. it is an addon, not its own LifeStraw model).



The second improvement that can be made addresses the device’s primary limitation: contamination at the mouthpiece. This improvement should offer a quick and effective way to sanitize the mouthpiece before and after each user operates the device. In practice, this could take the form of an added module attached to an existent LifeStraw that contains a small spray bottle of disinfectant. Again, this improvement needs to be low cost, easy to use, and preferably able to attach to an existent LifeStraw. Lastly, although minor, the LifeStraw could benefit from a small viewing window enabling the user to view inside and visually check the status of the filter. Will the new feature actually help the user? The flowmeter will help users and organizations (i.e. an aid group that distributes LifeStraws) track filter usage, which saves money and improves the overall effectiveness of the device. Devices can be used longer - there will be no guesses when the life of the filter is approaching its end. It will also allow users to track water consumption and maintain ideal hydration levels. With that being said, this feature is a luxury item both in price and in practice - its use does not impact the sole purpose of this device. The mouthpiece sanitation module will help in situations where the device is shared among multiple users. Contagions on the mouthpiece will not be transferred between users, which heighten the overall effectiveness of the device. However, individual users (such as a single hiker) may not see the explicit benefits that users in developing nations or disaster-victims see. The small viewing window may help in some situations to view the status of the filter. However, if the user were to drink from a substance (such as a dark liquid) it would most likely stain the filter that color. This may elicit a false positive from the user prompting them to replace the device even though it may be well within safe operating standards. As such, the applicability of the filter-viewing window is quite limited.



SolidWorks LifeStraw Models - No Improvements.

The above figure shows renderings of the original modeled LifeStraw. The logo is courtesy of LifeStraw’s website (http://www.vestergaard.com/our-products/lifestraw).

SolidWorks LifeStraw Models - Flow Meter Improvement

The above figure shows renders of the LifeStraw with the flow meter improvement. The flow meter is based off of a real-life flow meter that retails on Amazon (P3 P0550 Water Meter) for $14.99. It features a standard ¾” hose fitting male and female end. For this improvement the flow meter has been adapted to the turbine-variant as opposed to a pinwheel variant due to size constraints. The flow meter will come with two adapters that convert the ¾” flow meter fittings to the width of the LifeStraw fittings. This eliminates the need for a custom-made LifeStraw tube as the default one can be simply

http://www.vestergaard.com/our-products/lifestraw



used with the provided adaptors. The adaptors are internally contoured such that they preserve smooth laminar fluid flow. As mentioned, this improvement would be an accessory to the original LifeStraw and would sell with the flow meter and the two adaptors. The user would simply need to remove the bottom screen from the original LifeStraw and attach the fittings as seen in the figure. Ideally, the parts would be threaded for a tool/adhesive free assembly.

SolidWorks LifeStraw Models - Disinfectant Module Improvement

The above figure shows renders from the disinfectant module improvement. This improvement features a custom spray bottle that will be filled with a safe and environmentally friendly disinfectant. It has a threaded cap so it is refillable and is slightly larger than a typical chapstick tube. The spray bottle then rests into a holder that is contoured to the curves of the LifeStraw. The holder features two pins near the top where a rubber-elastic strap will attach. This will be pulled over the spray bottle to hold it into place when not in use. The holder attaches to the main LifeStraw body via two snaphooks. This attachment method eliminates adhesives and tools and can easily attach/detach to any LifeStraw with the corresponding snaphook grooves.



Bibliography [1] Evaluating Household Water Treatment Options: Health-based targets and microbiological performance specifications. (2011, January 1). Retrieved March 29, 2015, from http://apps.who.int/iris/bitstream/10665/44693/1/9789241548229_eng.pdf [2] Executive Summary. (n.d.). Retrieved March 29, 2015, from http://www.who.int/household_water/research/tsunami_summary/en/ [3] Frauchiger, Daniel, Roelie Bottema, and Mikkel Vestergaard Frandsen. Drinking Straw with Hollow Fibre Liquid Filter. Lifestraw Sa, assignee. Patent US8852439 B2. 17 Oct. 2014. Web. [Patent #2, Appendix Reference] Frandsen, Mikkel Vestergaard. Water Purification including Disinfection, Oxidation and Arsenic Removal. Patent WO2008025358 A1. 6 Mar. 2008. Print. [4] LifeStraw®by Vestergaard. (n.d.). Retrieved March 29, 2015, from http://www.buylifestraw.com/products/lifestraw-personal [5] Naranjo, J., & Gerba, C. (2011, October 10). Assessment of the LifeStraw Family Unit using the World Health Organization Guidelines for “Evaluating Household Water Treatment Options: Health-based Targets and Performance Specifications”. Retrieved March 29, 2015, from http://www.aspyma.mx/wp-content/uploads/2014/03/universidad_de_arizona_lifestraw_en_mexico_df.pdf [6] Product Manual [7] Prüss-Üstün, A., Bos, R., Gore, F., & Bartram, J. (2008, January 1). Safer Water, Better Health: Costs, benefits and sustainability of interventions to protect and promote health. Retrieved March 29, 2015, from http://whqlibdoc.who.int/publications/2008/9789241596435_eng.pdf [8] Walters, A. (2008, January 1). A performance evaluation of the LifeStraw : A personal point of use water purifier for the developing world :: UNC Electronic Theses and Dissertations. Retrieved March 29, 2015, from http://dc.lib.unc.edu/cdm/ref/collection/etd/id/1718

http://apps.who.int/iris/bitstream/10665/44693/1/9789241548229_eng.pdf

http://www.who.int/household_water/research/tsunami_summary/en/

http://www.buylifestraw.com/products/lifestraw-personal

http://www.aspyma.mx/wp-content/uploads/2014/03/universidad_de_arizona_lifestraw_en_mexico_df.pdf

http://www.aspyma.mx/wp-content/uploads/2014/03/universidad_de_arizona_lifestraw_en_mexico_df.pdf

http://whqlibdoc.who.int/publications/2008/9789241596435_eng.pdf

http://dc.lib.unc.edu/cdm/ref/collection/etd/id/1718



Appendix

Unmodified LifeStraw Drawing



Flow Meter LifeStraw Drawing



Flow Meter & Turbine Drawing



Flow Meter Adapter Drawings



Disinfectant Bottle Drawing



Disinfectant Bottle Holder Drawing



Disinfectant Bottle Holding Strap Drawing



Disinfectant Module LifeStraw Improvement

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BME 352 - Biomedical Engineering Design and Manufacturing ...michaelgbrowne.weebly.com/.../9/5/29959005/jd15-t-reverseengineeri… · BME 352 - Biomedical Engineering Design and Manufacturing