InnoCentive Solver Tom Kruer was featured yesterday in a story on Fox41 News, discussing his winning solution to the SunNight Solar mosquito repellent Challenge.  The piece provides a very interesting insight into one Solver’s story, including his background, some of his other inventions and his motivation to solve Challenges.  

Click the photo to see the full story.  Congratulations, Tom!

This blog entry describes, in detail the winning entry for the InnoCentive Challenge entitled “Reducing Risk of Malaria with Solar Powered Device”. The simple, passive solar device is shown in the illustration at left.

Not surprisingly, coming up with a viable solution to this Challenge involved the typical phases of product development project. Research uncovered the relatively few critical features that the product absolutely needed to have in order to be successful. The design phase generated and evaluated a number of alternative approaches which incorporated these critical features.  Two of these designs broke all the rules (including the ultimate solution) which the Seeker agreed to at least look at. A couple of crude functional prototypes were constructed to prove that the concept was feasible.  After that, it just was time to crunch some cost estimates and write up the submission for InnoCentive.

It must be pointed out that the Rockefeller Foundation and SunNight Solar deserve a great deal of praise for agreeing to publish this information and achieve as wide an audience as possible… with the ultimate hope of eradicating this terrible disease. 

The Research

My son, Nathan, and I started this project by doing extensive reading and analysis of the published research regarding the behavior of Malaria vector mosquitoes performed by leading universities and institutions.  It helped that Nathan is a student with access to a great university library and had an interest in winning some money (yes, I shared the prize with Nathan).

This literature review led us to two important conclusions that helped guide the rest of the design effort.  The first conclusion was that using insecticides for eradication was probably not the best idea as these toxic chemicals kill off as many or more beneficial insects as the target pests and mosquitoes eventually develop a tolerance to whatever insecticide is employed.

The second conclusion was that mosquitoes are attracted to their human blood hosts by the combination of the following factors when inside a human habitat (2):

1. The temperature of human extremities during rest (~ 29 +/-3 degrees C); and,
2. Moisture emanating from the skin; and,
3. The complex, multi-component scent of human sweat & resident microflora.

Once these conclusions were verified through more focused research, a device was designed to effectively attract, trap, and kill the female Anopheles mosquito by using a complete combination of the above three factors.

(1) There has been a great deal of scientific research into how carbon dioxide along with visual clues act as mosquito attractants.  However, when the research is evaluated in detail, it is apparent that CO₂ and visual indicators are used by the mosquito only when coming from a distance.  These attractants have little, or no effect within an enclosure.

The Design

The proposal which won the challenge is quite unique in that it uses a nontoxic phase change material (PCM) to retain passive solar heat during the day (see operation).  This stored heat is then released when the unit is brought indoors (when mosquitoes are feeding). Basically, the Eureka moment came when I realized that if all we needed was heat from the sun, we did not need expensive and complex photo-voltaic cells and batteries.  Inexpensive wax works just fine in a passive solar mode and phase change wax can be made to closely simulate human body temperatures.  Rough calculations showed that the released heat from only about 1 liter of paraffin wax, in combination with a natural convection chimney (analogous to a power plant cooling tower) distributes a water-based mosquito attractant throughout the enclosure for about 10 hours.

The black blow molded bottle which holds the phase change wax was initially configured to allow all the material to be approximately the same distance from an exterior surface.  This requirement led to a tall cylindrical shape with a large cavity in the center. The shape was further tweaked to provide the shape needed to achieve natural convection air flow.  A natural convection chimney was selected to achieve air flow instead of a motor-powered fan for what should be obvious reasons of reduced cost and complexity.

Phase Change Model

The third major aspect of the design was settling on which attractant to use.  The attractant suggested for use in developing third world countries is simply a small amount of water combined with human sweat (collected in a sweatband during the day).  It is noted that using sweat is a very simplistic approach, but it makes sense in so many ways.  First of all, sweat has been scientifically and experientially proven to work.

Therefore, this simple suggestion can be implemented immediately without any further research.  Secondly, there will always be a FREE supply of human sweat in the household… or from a more pungent “supplier” in the region (how about that for a job!).  Thirdly, research has found more volatile compounds in adult sweat that attract mosquitoes than found in other human fluids or artificially derived compounds.  And, again, its free.

The sweat attractant is located in a injection molded cup at the bottom of the unit with simple cotton wicks to expose the liquid to the rising air column. The cotton wicks could be cut from old clothing.  The attractant cup snaps into a hollow in the bottom of the phase change bottle.

The design also needed to offer a wide range of mountings since not all mosquito species fly at the same height from the ground.  Thus, the trap was design to be placed either on the ground (with the attractant cup providing an insulating thermal break for the heating element), on a tabletop, hung by a wire hook, or a pole up through the center of the attractant cup and the cavity in the heat element bottle.

Heat, moisture and scent are all present, thus meeting the critical requirements found in the research phase.  The mosquitoes are trapped in a simple tortuous path container placed on top and eventually die by dehydration.

Total manufactured cost was estimated to be roughly US $5.00 of material with assembly labor of an additional US $1.25.

An alternative design was also considered for this product.  This version positioned the phase change material in a plastic pouch which wrapped around a liquid trap. The trap mimicked nature’s pitcher plant which my son had seen in his travels to the rainforests of Peru .  Although equally unique as the final design, this design was deemed not as effective at distributing the scent nor trapping the attracted mosquitoes.

Operation

At the start of each day, the heating element/clear chimney assembly is removed from the attractant cup and placed on the ground, roof, or table outside the home where it can be exposed to the full sun.  At the same time, the sweatband is put around the ankle of the adult resident who is most frequently bitten by mosquitoes(2).

The phase change material within the black bottle melts during the day by absorbing heat from the sun.  The phase change assembly can be stood upright or laid on its side.  If stood upright, the flat surface of the chimney resting on the surface cuts off air flow through the hyperbolic gap and diminishes any cooling effect of wind or breezes.  Nothing will be damaged if it rains or tips over!

As the PCM heats up in the sun, the sweatband (or, alternatively, a cotton sock) will collect some sweat and foot odor from the “donor”.

At the end of the day, prior to dusk, the sweat band is washed with a few CC’s of water and wrung into the attractant cup.  The warmed heating element assembly would be placed back on top of the attractant cup with the conical surfaces ensuring proper alignment.  The trap would be placed on top of the heating element, if it had been removed.  Note that leaving the trap in place while the unit is heated by the sun may hasten the death of any entrapped mosquitoes.

At this point, it is recommended that the heated unit be placed in a dark corner downwind of beds or people in the habitat.  The reason for this is that the traps should be located in inconspicuous locations where they will not be disturbed or vandalized.  Furthermore, the research shows that mosquitoes search for hosts by traveling upwind, guided by scent.

Once inside the habitat, the heating element will begin to release its stored heat.  Heated air, laced with the moisture and scent from the cotton wicks, flows up through the hyperbolic gap between the bottle and chimney.  The air exits through the openings in the top of the trap and is distributed downwind to start attracting local mosquitoes.  Very intentionally, there is no CO₂ present in the air so as to avoid attracting more distant mosquitoes to the habitat.

The mosquitoes track the scent upwind to the trap rather than to the humans.  They find their way to the wicks only to find no host. The mosquito then takes off vertically and follows and/or are forced by the natural convective air flow up through the gap between the bottle and the chimney.  They pass through the trap holes into the trap assembly.  Once inside the trap, they cannot escape due to the tortuous path.

It is important to continually monitor the number of mosquitoes in the trap day to day.  If after several days the trap does not appear productive, it should be moved to an alternate location, or height.  Remember the primary goal is to trap blood-feeding mosquitoes. It is less of a priority to maintain consistent sites that may have poor yields.

(2) Note that the ankle is the preferred site for the cotton/elastic sweatband as a number of researchers have proven the effectiveness of foot odor as an attractant over other human scents.

A prototype of this solution will be built and tested by SunNight Solar.  If it is effective, SunNight Solar expects to begin production as early as this Spring.  For more on SunNight Solar and the malaria Challenge, click here.

We recently announced that a Challenge seeking the design of an affordable solar-powered device to prevent or limit the spread of malaria had been solved.  The Challenge was posted by Mark Bent, CEO of SunNight Solar.  Mark has been in the InnoCentive spotlight before, having previously posted a Challenge to create a solar powered light source for people living in off-grid areas of the world.

Mark’s interest in eradicating malaria comes from his own personal experience, and from his ongoing desire to help the world’s most vulnerable populations.  I asked Mark to provide some thoughts on the background of this Challenge, which he has kindly done in the post below.  Next week we’ll hear from the Solver of this Challenge, Tom Kruer.

Innocentive and SunNight Solar have recently announced the results of our latest cooperative effort – development of a device to trap and kill the mosquito which is the vector for malaria. With 300-500 million cases of malaria each year, resulting in immense societal and economic costs, over a million deaths and a child in Africa dying every 30 seconds from this disease, this is an effort SunNight Solar is very pleased to push forward to the product testing and commercialization stage. Our thanks to Innocentive, as well as funding from the Rockefeller Foundation, which has made this all possible.

I also wanted to offer some insights and developments which surprised me, and once again, showed another value proposition in participating in the Innocentive platform and this unique development cycle. I lived in Africa for over two decades and have contracted malaria twice, so I have some idea of the impact this malady has on the human body. I have also had friends die and I have seen the full hospital wards, so I have some first hand knowledge of malaria. Regrettably, with global warming, the range of mosquito infestation will no doubt grow and more people will be impacted by this disease in the future, so finding new ways to attack this age old problem is essential.

We thought outside the box – the two main ways mosquitoes are controlled is either barriers – nets and window screens, or chemically, via insecticides or sprays. Both have advantages/disadvantages, but also have their limitations. You cannot stay indoors or under a net all of the time and chemicals have a number of unfortunate, and sometimes deadly, consequences. So, we offered a challenge – what can we do with solar energy to produce a device, under $10, to kill, repel or sterilize the female mosquito?

Frankly, I thought we would have some variation on power generation and battery storage – a photovoltaic panel which generates electricity, stored in rechargeable batteries, powering some device, much like our solar lights, and in fact, the majority of the offered solutions fell into this category. However, the solution we selected was in fact not power generation at all, but passive solar energy collection – a device which heats in the day’s sun, retaining that heat in the evenings when the mosquito becomes active, thereby cleverly mimicking a warm human body at rest. What a great idea and one – without InnoCentive – I would never have considered on my own.

So, we are going to start producing this device within the next few weeks and hope to start field testing and deployment in the second quarter of 2009. The science and logic appears quite solid and we have high hopes this device will work effectively and become part of the human arsenal deployed against this deadly disease. Innocentive and SunNight Solar will openly report the results of the field testing – whether successful or a failure or somewhere in-between. I want to state emphatically, however, in my mind, this is already a success, because we are taking the chance, even with the risk of failure.

This is the unique value of the Innocentive/Rockefeller/SunNight Solar partnership – going out into new areas, taking risks, developing new approaches to age old problems – lighting at night, mosquito control – and doing it in a manner which brings together the brightest minds in the world and avoiding the ‘silo’ approach of one company, one research and development department, only one team. With Rockefeller Funding, Innocentive open platform and the world’s problems – this is the way to make a real difference in innovation and science. My personal thanks to all the solvers, the Innocentive team and the strong support from Rockefeller.

Warmly,

Mark

Therefore, participating in open source innovation, as facilitated by InnoCentive, seemed like a natural fit for me. During the few months since I started offering solutions, I have been amazed at how many other Engineers and Scientists out there are also open to doing things differently. I may have found my clan!

And what a clan! We are acting as change agents for how problem solving, innovation, and product design may be done in the future. We are probably shaping the new way intellectual property will be generated and protected going forward. We may even be starting a totally new way to conduct business virtually. If you can do open Product Design and Marketing, why not Accounting and Manufacturing? (InnoCentive should owe me an award if they use that one!). From my perspective, we are participating in this truly amazing experiment of open innovation at a truly extraordinary time in history. I find this exciting!

But I also find it the basis of hope. If one views open source innovation, as exemplified by InnoCentive, as a harbinger of how we might solve the much bigger challenges that face us in the world, my heart lightens. People say that the world has so many “problems” (war, oppression, decease, poverty, water shortages, overpopulation, etc). I would love to see those in power use the open source model and turn these “problems” into “opportunities”; Opportunities for grass roots efforts of creative and motivated people from all types of backgrounds and disciplines to come together and implement much-needed changes. But, again, I am open to dreaming.

In closing, I must thank you, my esteemed colleagues, for the enjoyable competition that you have provided me on the InnoCentive website. I feel honored to be included in your ‘clan’, given your impressive backgrounds, extraordinary credentials, and inspiring creativity. Keep up the good work.