Date: January 2017.
Source: NewScientist

Diaper tech: inspired by babies
NOT many research facilities have walls decorated with giant bumble bees and paddling ducklings. Nor do they tend to distract their study subjects with colourful slides and miniature shopping carts.

Pampers – the first brand to widely introduce disposable diaper technology – has been understanding the needs of parents and babies to create new innovation for over 50 years. At the P&G Diaper Research and Development Centers in the US and Germany, around 250 researchers, part of a global team of over 800 scientists, ranging from dermatologists and chemists to material engineers, are designing the diapers of the future. The creative power of this team has enabled P&G to file more than 5000 diaper-improving patents.

Babies in motion: 3D scanning: Disposable diapers have changed beyond measure since their beginnings in the late 1940s. Their chief purpose, however, remains the same: to minimize leaks and keep skin dry and healthy and babies comfortable.

To help achieve this, babies and toddlers are regularly invited to the child-friendly research suite in Germany. The shape, fit and movement of their diapers are observed as they play. Detailed measurements are made in a large 3D scanner, consisting of 20 synchronized cameras arranged around a platform. Down the corridor is a specialized lab where dermatologists measure skin pH and loss of water from the skin as part of their efforts to minimize skin irritation.

Researchers also give packets of diapers to 1,200 families a week. These may be experimental designs or existing products. Parents are asked to keep a diary of how each performs, detailing such things as leaks, shape changes and dryness and condition of the skin.

This feedback is combined with the properties of materials in diapers, such as elasticity and absorbency, to create computer models of new designs. These are used to calculate the chances of a leak or excessive sagging, for example. “We can assess 20 virtual diaper prototypes and eliminate all but two or three,” says Dr Frank Wiesemann, P&G Principal Baby Care Scientist. “We then test those fully, rather than testing all 20.”

Channelling innovation: Germany plays a key role in delivering major innovations in diaper design. Below the permeable sheet next to the baby’s skin, for example, most diapers have a polymeric “acquisition layer” that draws urine away from the skin. P&G’s scientists have added a second “distribution layer” to Pampers diapers, which disperses liquid around the diaper so it can be absorbed more efficiently. This is mostly made of cellulose, long thin fibers extracted from wood pulp. P&G treats them to create short “cross links” that strengthen the fibers (see graphic). This helps the diaper absorb quickly, even when a child sits on it when it’s full.

Liquid flows along gaps between the closely bound cellulose strands which act like capillary tubes. “You need active distribution of the urine, whichever position the baby is in,” says senior P&G scientist Dr Ute Fröhlich. “Capillary forces between the cellulose fibers are high, so urine can move rapidly even against gravity.”

Most of the liquid then passes to the absorbent core layer of the diaper. Until recently, the core of a Pampers diaper resembled those of some other brands: a mixture of cellulose and particles of super absorbent polymer capable of soaking up huge amounts of liquid relative to its own weight. The idea was that the cellulose initially soaks up the urine and the super absorbent polymer dries out the cellulose. However, it is impossible to dry out the cellulose completely, so urine can be released back to the skin under pressure.

To deal with this, P&G developed a new super absorbent polymer that absorbs urine more quickly, letting them eliminate cellulose from the core. This has cut the weight of a single Pampers by around 5 grams, or 16 per cent, which is good for children. In a study funded by P&G, psychologists at New York University showed that, compared with cloth diapers, thin disposables help toddlers to keep their feet, reducing stumbles and falls.

Some super absorbent polymers can take up hundreds of times their own weight in liquid, but P&G has constrained the new version to absorb between 20 and 30 times its weight. As a result, the particles do not merge into a single jelly-like blob. They stay as individual spheres even when saturated, so that any extra urine can flow past them to be absorbed elsewhere.

Innovation doesn’t end there. Some diapers leak as a result of losing their shape when worn by active infants. To minimize this, P&G recently shaped the core into three channels to help the diaper keep its shape.

Finally, feces are trickier to deal with than urine. Clinical studies have shown that the enzymes in feces can be aggressive on baby skin, especially when activated by high pH urines. So quick removal of feces from the skin reduces the risk of diaper dermatitis. To improve performance, a Pampers Premium Protection diaper has a top sheet that has little conical apertures, allowing feces to get into the core instead of spreading on top. This reduces feces contact with the skin.

“When I chose to study chemistry I didn’t set out to become a poo and pee expert,” says Fröhlich. “What I didn’t realize then was quite how much amazing science there is in the modern diaper.”

Article: All you need to aim to create the driest, most comfortable diapers is a lab full of playing babies and some bright minds.
Authors: Sponsored by P&G