Materials on a mission

Materials World magazine
,
1 Feb 2018

Ledetta Asfa-Wossen examines the shrewd material innovations underway to address humanitarian needs.

The World Health Organisation estimates there are at least 30 million people in low-income countries in need of mobility devices and other assitance technologies, but a prosthetic limb alone can cost up to US$1,875 in the developing world. In answer to this, e-NABLE – a 3D printing prosthetics initiative led by a global team of researchers, volunteers and engineers provides amputees in Sierra Leone with materials knowledge and access to 3D printing technology to design their own affordable, custom-made mechanical hand. 

There are many more humanitarian engineering examples. From solar-powered rechargeable hearing aids developed by a firm in Botswana, called Deaftronics, for communities with no access to audiology facilities, to life-saving LED phototherapy devices to treat severe jaundice among newborns in India, South Africa and Peru.

Khanjan Mehta, founding director of the leading humanitarian materials engineering department at Penn State University, USA, and now director of a similar programme at Lehigh University, USA, explains the latent potential of materials science in this field. 

‘There are more and more programmes emerging to address challenges in developing countries and they could all benefit from having an emphasis on materials engineering. 3D printing has become a game-changer and while we may have more work to do in terms of developing stronger plastics and optimising metal 3D printing, we are on the right trajectory.

‘I’m a huge fan of cradle-to-cradle design (viewing materials as nutrients in healthy, safe metabolisms) and the more we can learn about natural materials to make products, especially consumer products, the better off we will all be. There’s also the added benefit of creating local jobs and spurring frugal innovation.’

Engineering change

Mehta discusses some of the projects that arised from Penn State’s materials research and humanitarian engineering collaboration. ‘As a team, we designed and commercialised affordable greenhouses and we’re now working on low-cost diagnostic devices, like paper test strips to test for diabetes and screen women for urinary tract infections. These strips are manufactured by stamping – it’s inexpensive and appropriate and eliminates the long assembly line involved in extensive conventional manufacturing processes.’

The paper strip sensor changes colour to indicate infection or glucose in a person’s urine and the test strips can be printed using a foam stamp at very low-cost. But, it’s not all about the technology, says Mehta. Instead, he insists on a market-centric approach to design, turning technologies into local, self-sustaining business opportunities. The low-cost greenhouse design aimed at East Africa is the perfect example of that. 

While in rural Kenya, as Mehta was working on a telemedicine system with his team, it came to light that a greenhouse could help locals earn just enough to access basic healthcare. The greenhouses cost over $2,500, far more than what most farmers can afford. However, with a new design, the materials to make them could be reduced to $350, subsequently creating a cheaper product at between $600-$1,000. 

Mehta is keen to highlight the materials expertise that was needed for the innovation to come to fruition. The team went through 12 to 15 designs before finding one that worked. Steel was too heavy, expensive and prone to damaging the glazing during heatwaves, while polyvinyl chloride (PVC) lacked durability and the ability to withstand UV rays and high temperatures. 

‘Everything we do has to be ruggedised [sic] to adapt and survive under pretty harsh conditions and understanding these materials play an important role in letting us know if a product will stand up to factors such as temperature swings, harsh UV radiation, chemical exposure, shock, vibrations and humidity,’ Mehta explains.

The current design consists of timber and greenhouse-grade plastic – a woven polyethylene material. ‘Initially, we used connectors made of bamboo to hold the glazing and a greenhouse frame made of repurposed polypropylene random copolymer pipes (PPR) but the material warped when heated and while the structural integrity was unaffected, we had concerns about the aesthetics,’ says Mehta. ‘The lack of availability of PPR in some countries, compared to local timber, also became an issue. In Kenya, we were able to effectively use blue gum in the frame design, which is durable and keeps costs low.’ Most greenhouse-grade plastic in East Africa is sourced from Israel, Europe and the USA, and is expensive. 

The team, with the help of a materials characterisation lab, is now looking into the use of coated rice sacks as a lower cost alternative to greenhouse glazing traditionally made of glass, PVC, polypropylene and polyethylene.

Working backwards

Finding a solution for unstable and often extreme environments requires an entirely different method of investigation and the conditions can be challenging.

Engineers in this field have to think in a different order. Mehta explains, ‘There are significantly fewer options for materials that can be used for products being designed in low-resource settings. Often, the first question is whether the product will be made locally or imported from a country with a good manufacturing base? For instance, some of the most successful products in African countries are manufactured in China or elsewhere because making them locally would increase the prices significantly and place them out of the user’s reach.’

He adds, ‘There is also the question of supply chains, infrastructure, talent for manufacturing and assembly and access to reliable power and enabling technologies that can make it difficult to manufacture materials or end devices in developing countries.’

The characterisation processes requires specific expertise and resources that aren’t available outside of large corporations and elite research labs. Furthermore, there is no standardised process, since product needs strongly depend on the context and user base, making it onerous for underfunded start-ups and academic groups to bring innovations to market in a cost-effective and timely fashion.

A question of funding?

While it may be difficult, Mehta believes ‘there is so much life-changing potential’ for materials engineering. ‘Every day I hear of someone finding a new use for activated carbon. But I also hear of innovators struggling to figure out how to manufacture their product so that it will stand the test of time. It seems to me that there is a lot of funding devoted to fundamental applied research but not as much dedicated to make new knowledge accessible and usable for innovators working in low-resource settings.

‘If we invested as many resources on water filtration or low-cost diagnostics as we do on the resolution and image quality of our televisions, the world would be a very different place.’

He adds that humanitarian engineering is still very much a new concept across academia. It is not a field for the weak-willed, but the rewards are rich and the stream of innovation has been commendable. ‘There is an enormous amount of money to be made by designing and commercialising useful innovations in developing countries and those products can be transformative in improving the quality of life for people in those countries. It’s really not a zero sum game – we are all in it together and our destinies are intertwined.’

Rapid concrete structures

A cement-impregnated fabric that hardens when hydrated to form a durable, waterproof and fire-resistant concrete shelter has been devised by Concrete Canvas, a company that develops shelters for humanitarian disaster relief.

The shelters can be inflated without the need for plant or mixing equipment. The permanent structures have a design life of 10-plus years and are shipped in airtight sacks that can be taken apart and constructed in less than an hour. 

The canvas comes attached to a polyethylene frame that forms a Nissen-Hut shaped structure once inflated. The robust structure is ready to use in 24 hours and has been modelled to withstand high compressive loads, shrapnel, blasts and small arms fire. In August 2017, Concrete Canvas was used to remediate a dilapidated culvert in Laurencekirk, Scotland.

Waste banana fibre

Over 88% of women in India depend on alternatives to sanitary towels due to cost, according to a report by research institute, Nielsen (formerly known as AC Nielsen). MIT graduate Kristin Kagetsu and three other co-founders from Harvard and Nirma University have developed Saathi pad – a 100% biodegradable sanitary towel made from waste banana tree fibre.

The stems of banana trees are bought from collectives of local farmers. After extracting the fibre, the residue left over can be fermented and used by farmers as an organic fertiliser. Most plastic sanitary pads use around 3.4g of plastic and a chlorine-bleached wood pulp as an absorbent, while many eco-friendly pads use cotton. The researchers claim banana fibre uses six times less water per tonne produced than cotton