Fabric + shape = a mask that fits your face uniquely | MIT News

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Form-fitting clothing is not always determined by clothing choices. For example, the global pandemic has underscored the need for face masks that effectively seal the nose and mouth. But faces and their features differ from person to person and can make one-size-fits-all face masks less effective. Well-fitting masks have proven to be a coveted accessory.

Lavender Tessmer, a graduate student in MIT’s Department of Architecture, has developed a new active fiber and designed a process that – combined with a specific knitted textile architecture – uses heat to activate a mask to conform to a person’s face . With the standard textile equipment and the new customization process, each manufacturer can create a custom mask.

Before Tessmer joined MIT in 2017, he had no formal initiation in textiles. She began collaborating with Skylar Tibbits, associate professor in the Faculty of Architecture and founder of the Self-Assembly Lab, where his research topics include programmable materials—simple materials that can be activated to perceive, respond, and change. The following year, the lab purchased an industrial flatbed knitting machine, which is ubiquitous in textile manufacturing around the world, and Tessmer set to work learning how to operate it.

“It has a tremendous learning curve and there are endless things you can do with a machine like this,” says Tessmer.

Her early start on the knitting machine was anticipatory of the work to come.

A head start

A few years before the pandemic, Tibbits’ lab received a grant from Advanced Functional Fibers of America (AFFOA) to develop “smarter textiles” that would be able to sense, react, and change. The research led to a partnership with Ministry of Supply – a fashion company specializing in high-tech apparel – to develop a new system for ‘smart textiles’. Founded by MIT graduates, the Ministry of Supply uses temperature-regulating fabrics to design and manufacture environmentally responsible clothing for professionals.

In the spring of 2020, a confluence of events changed their collaboration. The global pandemic forced businesses to close in March; The architecture faculty called for proposals to fund research positions for students to work with the faculty on “crisis-related research,” including designing responses to the pandemic; and the need for masks to protect first responders and the general public became apparent. Tibbits’ research was funded by the Ministry.

“Lavender was already trying to make textile garments with a custom fit, so we could quickly move on to making custom masks,” says Tibbits. “But the biggest challenge with any customization is that you can’t make every mask unique. It becomes a factory logistics problem. You must be able to mass produce these. Customers don’t want to wait weeks or months for their one-of-a-kind mask.”

So how is a mass-produced mask tailored to an individual face?

“Lavender created the knit structure—the architecture—of the mask,” says Tibbits. “The material properties alone do not lead to the behavior of the precise transformation. They are basically two or three dimensional knit structures and with every single stitch you can change the structure and the materials.”

Tessmer also developed one of the two active fibers (the other was already commercially available), which is needed to respond to heat so the fabric can be controlled in a predictable way.

“There had to be a clear correlation between the amount of heat applied, the method of application with the robot, and a predictable result in the dimensional change of the tissue,” says Tessmer. “It was an iterative process between developing the multi-layer fabric, measuring its dimensional change, and finally being able to have the robot apply heat in a repeatable and predictable manner.”

There were already guidelines for existing measurement ranges of human facial features in the public domain. The mask’s initial shape is large enough to fit almost any face before it’s transformed and adjusted. From there, Tessmer entered measurements of a person’s face, and the knit masks were activated with a robotic arm equipped with a heat gun that applies heat in specific patterns to precisely fit the facial measurements.

Covid-driven need for masks

With their retail stores closing early in the pandemic, the Department of Supply switched from making clothes to making face masks.

“The strength of Lavender and Skylar’s work is that it leverages additive manufacturing techniques that can be deployed to production very quickly,” said Gihan Amarasiriwardena ’11, co-founder of the Ministry of Supply and president of the company. “Working with the Self-Assembly Lab, we were able to design, test and develop a mask in five days and have 4,000 masks made for healthcare workers in two weeks because we can use 3D computer aided knitting. I think this will be a key benefit to redirect existing materials to masks very quickly in the future.”

“The goal was to redesign a mask to fit every face perfectly, which is a big challenge with masks and other clothing items,” says Tibbits. “No one has really figured out how to do this, other than hiring a tailor or having a lot of standard sizes that don’t fit perfectly.”

It’s important to note that Tessmer and Tibbits’ work focused on a mask’s fit and not the properties needed for the mask material to filter out particles in the air – although a standard filter could be included to improve its effectiveness. The masks are also reusable and washable.

“Our goal was better fibers and a controllable, repeatable process for producing a precisely fitting mask,” says Tessmer. “We created masks for nine different people to demonstrate how effective the process is.”

Last fall, a paper they co-authored, titled “Personalized Knit Masks: Programmable Shape Change for Customized Fit,” included instructions for creating “truly customizable masks” that fit each person’s unique facial features. The Association for Computer Aided Design in Architecture (ACADIA) honored Tessmer and Tibbits with the Best Paper Award for this groundbreaking work.

“The award recognizes work as exemplary and presents innovative research with substantial contribution to the described field,” the jurors stated in their comments. “The paper not only demonstrates rigorous research methodologies and disciplinary expertise, but is also well-written and brings new insights to the ACADIA community and beyond.

The development of SARS-CoV-2 variants suggests the need for high-quality masks remains, and the US Centers for Disease Control continues to support their use. Amarasiriwardena believes consumer interest and the need for masks will continue, albeit seasonally, as people become more indoors. He says that a mask’s fit and comfort is the second question customers ask about the effectiveness of the filter media.

“The overall effectiveness is tied to the fit, which is unlocked through personalized manufacturing,” says Amarasiriwardena. “The Self-Assembly Lab has truly pushed the boundaries of additive manufacturing and their recent work in textiles combines their expertise in ‘hacking’ CAD-CAM flows to create truly novel soft goods. While much of the attention has focused on 3D printing hardware, their innovation in textiles shows widespread application of self-assembly technology.”

According to Tessmer, the masks were a great case study because they have been a coveted accessory in recent years and there have been noticeable issues with the masks fitting. She would like to apply the process to other types of clothing and accessories, such as sweaters and shoes.

“At the end of every project there are always things that need to be improved,” says Tessmer. “For example, there are many future material developments. But I’m happy with the project because it’s a working proof of concept for my idea and I’m confident it will work.”

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