Interview with Brad Holschuh
We can now create textiles, garments that change shape over time
A new study led by researchers at the University of Minnesota's Design of Active Materials and Structures Lab (DAMSL) and Wearable Technology Lab (WTL) details the development of a temperature-responsive textile that can be used to create self-fitting garments powered only by body heat. Brad Holschuh, co-director at WTL, explains to Rajesh Kumar Shah the breakthrough invention in wearable technology, which has the potential to change how we interact with the clothes we wear every day.
TT: Your research focuses on the novel use of wearable actuation systems to improve human health and performance. What led you to develop interest in this field?
I originally worked on research problems associated with human spaceflight, where advanced technologies are necessary to keep astronauts healthy and high performing in orbit and in deep space. It became clear that the technologies that we were developing had great potential to solve problems on earth in everyday life; so, I expanded my research focus beyond human spaceflight topics.
TT: What are shape-changing materials? What are the advantages of using such materials in wearable technology?
Shape changing materials-active materials-are a category of materials that exhibit controllable transformation capabilities. Meaning, these materials can be stimulated in some way- electricity, temperature, light, pH, etc-and they will react with a physical / mechanical transformation. These types of materials are appealing because they offer actuation capabilities in form factors that are often superior to typical actuators (e.g., hydraulic systems or servo motors). If we are interested in creating on-body actuation-meaning, creating mechanical effects on the body such as forces, torques, displacements, tensions, pressures-the form factor and functional properties of some active materials offer exciting opportunities to create textiles with embedded actuation abilities, and those have many potential uses cases in the wearables space.
TT: Your team recently made a breakthrough invention of shape-changing textiles powered only by body heat. Please throw some light on this.
This innovation includes materials innovation, textile innovation and garment innovation. From a materials perspective, we have worked with engineers to create a form of shape memory alloy (SMA) - alloys which change shape when heated-that respond upon exposure to the passive heat generated by the human body. From a textile perspective, we have created 2D knitted fabrics comprising this SMA material, and these knits can be engineered / architected to create custom 2D actuation behaviour, including both contraction (to support compression applications) as well as out-of-plane bending (which would support textile movement to conform to irregular body topographies).
TT: Which active materials are used in this invention? What is their special property?
These are shape memory alloys- SMAs-which are a metal alloy (typically nickel titanium, NiTi) which change their shape in a repeatable fashion when heated through a temperature range.
TT: How is this invention expected to change the way people interact with the clothes they wear every day? How is it expected to help the physically challenged?
We can now create textiles and garments that change their shape over time, in particular when they first come into contact with the user's body. This has widespread significance for garment design, as it means that garments that might otherwise need to be tight fitting (e.g., compression garments, socks, corsets, even shoes) need not be tight fitting 'initially.' So, the user can easily don these garments without difficulty, and the garment can subsequently react to tighten around the wearer. This is particularly exciting for individuals with physical limitations, who may otherwise struggle to don their clothing, as this alleviates the effort required to put on a tight-fitting piece of clothing.
TT: How big was your research team and how long did it take to come out with this breakthrough invention?
This project was a collaborative effort between two laboratories at the University of Minnesota (UMN)-the Wearable Technology Lab (WTL ) in the College of Design and the Design of Active Materials and Structures Lab (DAMSL) in the Department of Mechanical Engineering- as well as researchers at the NASA Johnson Space Center (JSC). The primary team at UMN was myself, Prof Julianna Abel (as Co-PIs), and the research was led by two graduate students-Rachael Granberry and Kevin Eschen. This work has been ongoing since 2016.
TT: Please give some examples of the future use of shape-changing textiles. How are they different from wearable technology?
They aren't different than wearable technology-they are wearable technology, though they may appear different from the forms of technology that are commercially available today. Shape-changing textiles in the wearable section create many opportunities to design clothing with physically dynamic properties. Examples could include compression garments that can be strategically tightened, shoes that can self-tighten, clothing with fit properties that can be customised to the user, or even exoskeletons to provide structural support or mechanical support to people with mobility problems. They also have advanced technology applications, such as for future space suits or compression garments for pilots and astronauts.
TT: What will be the next step of research at Wearable Technology Lab?
Our lab is actively working on several projects. On this project specifically, we are continuing to refine the materials, investigate new fibre and textile configurations with appealing actuation characteristics, as well as garment prototyping for user testing in a variety of capacities. (RKS)