Aims: 1. Development and validation of fabric-based flexible pressure sensor with the ability to measure an ultra-wide range of pressures 2. Validation of pressure sensors for use in gait analysis using an instrumented split-belt treadmill

Motivation: Conventionally used force plates for gait analysis are expensive and bulky and cannot be used for monitoring gait outside of laboratory settings. A critical need exists for low-cost pressure sensors that can be integrated with footwear or real-time gait analysis in the patient’s natural environment.

Technology: The sensing approach for the development of these pressure sensors is based on the formation of electrically conductive nanocomposite films of functionalized carbon nanotubes. The carbon nanotubes can be deposited on a variety of common fabrics such as polyester, nylon, wool, and aramid. The electrically conductive nanocomposite coating is only ~500 nanometers thick, chemically bonded to the fiber surface and shows piezoresistive electrical/mechanical coupling. The pressure sensor displays a large in-plane change in electrical conductivity with applied out-of-plane and has the ability to detect a wide range of pressures from tactile to thousands of tons. Preliminary experiments have been conducted by integrating these sensors into footwear with subjects walking on the split-belt treadmill. All the steps were detected by the sensors in the footwear and provided a reliable averaged peak force measurements at different walking speeds.

PI: Dr. Erik Thostenson – thosten@udel.edu; Collaborators: Jill Higginson

Flexible Pressure Sensors Integrated with Footwear for Gait Analysis

Sensor Values for a Gait Cycle using Instrumented Footwear

Ultrahigh Sensitivity for Detecting Joint Motion by Depositing Carbon Nanotubes on Everyday Fabrics

Aims: 1. To develop an internal open-access anthropometric database of UD collegiate basketball players using 3D body scanning technology 2. To design and prototype facial masks for the target population using novel materials, such as carbon fiber infused thermoplastic polyurethane and shear thickening fluid embedded textiles 3. To conduct material and wear testing for the face masks, in comparison to standard masks

Motivation: Standard masks reduce player visibility due to fogging from perspiration and peripheral blocking. Lack of custom fit and hard plastic materials create discomfort and can distract injured athletes during play. Custom-fit masks made with improved materials would be preferred by athletic trainers for both collegiate and professional teams. However, accessibility, cost, and lack of evidence-based research have created a barrier to improving the current standard of care.

Technology: A 3D full-body scanner is used to record the body measurements of the basketball players. The digital replications are created using a CAD software and then 3D printed. Experiments are being conducted synergizing different materials to determine which mixture yields the greatest comfort with the greatest protection. The custom-fit masks are compared to the commercially available masks. The players wear masks during practices while replicating competition-style activities. Play is video-recorded and behavioral coded using Datavyu software. Researchers also interview and audio record the players to determine visibility and comfort levels. Further, we will material test and compare the custom masks to standard masks independently of the wearer to determine the max force load.

PI: Dr. Martha Hall – mlucinda@udel.edu

Aims: 1. Conduct patient research to identify design criteria to meet the functional design requirements for a compression sleeve/stocking for the treatment of lymphedema 2. Design a compression garment that meets the user-driven design priorities 3. Manufacture and test a functional prototype of the compression garment

Motivation: Lymphedema is a pathological ailment, normally displayed as swelling due to a chemical imbalance. Current treatment methods for lymphedema include exercise, reducing stress, eating fruit and vegetable-rich diet, bandaging the extremities, massages, pneumatic compression, compression garments, and Complete Decongestive Therapy (CDT). However, all of these methods have some form of health risk contraindication. Compression garments are pieces of clothing made of varying materials that fit tightly around the body. Compression garments allow for support and comfort for those struggling with varied ailments, including lymphedema. The compression garments work by creating a pressure gradient in the affected limb. This causes a flow of fluids from a high concentration in the area of which they are accumulating, to an area of low concentration, with little to no fluid acclimation. This gradient movement helps to reduce the pain and swelling. The key challenge is that current compression garments are (1) difficult to don and doff by the patient, (2) uncomfortable, and (3) unattractive to wear.

Technology: Using the Anthroscan 3D Body Scanner (Human Solutions) and the WHOLEGARMENT knitting machine (Shima Seiki), we custom design and manufacture a compression garment based on user-driven design metrics. The body scanner provides extreme accuracy for patient measurements, as well as allow for pre/post scanning of the affected limb. The knitting machine allows us to design a modular compression garment using any fiber, identified as comfortable and aesthetically pleasing to the end-user.

PI: Dr. Martha Hall – mlucinda@udel.edu

Aims: 1. Develop heated garment prototypes that are capable of providing a broad range of programmed therapeutic temperatures that can be powered either through a battery or external source 2. Design and integrate portable and efficient electronics to control the heated garments using temperature feedback from the user's body 3. Test electrical reliability and safety, heating performance, and validating the electronic components

Motivation: Due to increasing obesity, accidents and aging, joints in the human body are often injured hindering quotidian activities such as walking and other movements. Thermal therapy is one of the classical physiotherapies used in orthopedics to alleviate the symptoms of pain, swelling, and numbness. The primary objective of this research proposal is to develop low-cost, comfortable to wear innovative garments with heating capabilities and their control electronics which can be used for thermotherapy.

Technology: The key driving technology for creating heated garments is the ability to deposit conductive nanocomposite films on different fabrics to enable Joule heating capability without compromising the flexibility and comfort of end-user. The applied voltage and the current will be controlled microcontroller. It allows for the most flexibility regarding providing accuracy and functionality for the heated garment. With a built-in analog-to-digital converter (ADC) and I/O pins, the microcontroller will support multiple connections to the textile material to provide heat.

PI: Dr. Fouad Kiamilev – kiamilev@udel.edu, Collaborator: Erik Thostenson – thosten@udel.edu

Self-heating fabric by depositing carbon nanotubes on it (b) thermograph using an infrared thermal imaging camera showing temperatures of 72°C. Table (inset) shows the temperature values with increasing voltage

Aims: 1. Evaluate variability of breast support in different sweat conditions, using 3D body scanning and pressure sensors 2. Create a responsive sports bra prototype aimed at optimizing breast support in various sweat conditions 3. Evaluate responsive sports bra prototypes using human subjects wear trials

Motivation: The sports bra design and innovation has evolved from the first general exercise bra, recent studies report that 75% of female marathon runners experience bra-related issues. Due to the geometrical complexity of the anatomical structure of women's breasts, designing bras with effective breast support is complicated and challenging. Continuous and repetitive movements without breast tissue support can result in breast soreness, pain, and sagging. Studies on graduating breasts compression engineered via seamless knitting technologies, and using moisture responsive materials, have significance for the overall compression garment market, including recovery garments for performance sports as well as for medical fields (breast cancer survivors, veteran’s amputee and surgery recovery).

Technology: New advances in fiber technologies are now producing superfine wool fiber blends that are feasible moisture responsive materials. Moreover, the advanced computerized knitting technologies such as Santoni seamless machines and Shima Whole Garment systems allow for detailed engineering of the knitted stitches at the yarn tension, loop size and yarn combination levels. Studies of moisture responsiveness at the knitted textile level will use air permeability and fabric thickness evaluations. To evaluate the variability of breast support in various sweat conditions, a control sports bra sample will be used, developed in a previous study, and subjects will be wear-testing it in various sweating conditions, running on a treadmill. Additionally, a questionnaire will ask the subjects to evaluate perceived breast support and comfort in various sweat conditions. The new prototype will be designed and evaluated based on data analysis from 3D body scanning and pressure sensors worn by the subjects.

PI: Dr. Adriana Gorea – agorea@udel.edu

Study of the deformation of various knitted structures actuated by moisture

Study of sports bra compression variations using 3D Body scanning

Aims: 1. Development and testing of user-controlled exoskeletal garment (Playskin Air) for arm movement impairments.

Motivation: Many individuals have difficulty moving their arms against gravity to engage in daily activities due to diagnoses such as cerebral palsy, muscular dystrophy, or stroke. Exoskeletons, wearable devices that can provide movement assistance, have the potential to improve arm function for individuals with arm weakness. However, existing exoskeletons are often made of hard components that are bulky, expensive, and uncomfortable. Thus, they are not feasible for use in natural environments where end-users live and function.

Technology: The Playskin Air™ is a soft, user-controlled, pneumatic exoskeleton developed to support arm function for individuals with physical disabilities (figures illustrate bench testing of the soft actuators on a model with the weight of an 11-year-old male’s arm). The Playskin LiftTM is the first soft pneumatic exoskeleton aiming to fully support the full weight of users’ arms.

PI: Dr. Michele Lobo – malobo@udel.edu; Collaborators: Huantian Cao

A Schematic Figure and Photograph of the Active Garment and Test Setup

Aims: 1. Qualitatively examine the perceived utility of current physical activity wearables and the proposed M2 Band among adults with ID, their caregivers, and physical activity interventionists 2. Assess the usability, accuracy of measurement, and social feasibility of the M2 Band with a sample of individuals with ID and their caregivers.

Motivation: Compared to the general population, adults with intellectual disabilities (ID) are significantly more likely to have cardiometabolic conditions such as obesity (58.5% vs 35%) and cardiometabolic risk factors such as lower physical activity. For example, only 9% of adults6 and 13% of children with ID meet the physical activity guidelines. Current methods to motivate this population to be active are heavily reliant on the presence and support of caregivers and experts. The complexity and high-tech nature of current technologies that track and motivate individuals to be active are frequently incongruent with the cognitive ability of adults with ID; this has been identifying as a reason for the insignificant results in physical activity interventions involving wearable devices for adults with ID. The development of simpler methods to motivate this population to be independently active is critical to combat the health disparities they experience. There is a critical need to develop a device that tracks and motivates movement in individuals with ID.

PI: Dr. Martha Hall – mluncinda@udel.edu and Sean Healy – healys@udel.edu

Aims: 1. Conduct patient research to identify design criteria to meet the usability, comfort, and aesthetics requirements for the Functional Fabrics AFO 2. Design a Functional Fabrics AFOs that meets the consumer-driven design priorities 3. Manufacture and test a functional prototype of the Functional Fabrics AFO

Motivation: Ankle foot orthoses (AFOs) are a type of orthotic brace prescribed to individuals with ankle joint impairments or injuries with the goal of supporting and aligning the ankle joint to improve gait, and thus patient mobility, activity, and participation. AFOs are the most commonly prescribed orthotic device and are used by numerous patient populations including individuals who have suffered a stroke, individuals with Cerebral Palsy, individuals with traumatic orthopedic injuries who have undergone a limb salvage procedure, as many other individuals with neuromusculoskeletal injuries or impairments. In 2016, Medicare expenditures for orthotics reached approximately $1 Billion. Most AFO users have to wear their AFO from the time they wake up until the time they go to sleep in order to safely and effectively go about their days, essentially making their AFO as critical to their daily life as the clothes they wear.

PI: Dr. Martha Hall – mluncinda@udel.edu and Elisa Arch – schranke@udel.edu

Aims: 1. Demonstrate that mechanical models of textile materials can be used to quantitatively capture the actual human-fabric interactions 2. Use those validated mechanical interactions to demonstrate the potential for integration with current biomechanic modeling

Motivation: The need for assistive devices such as exosuits and artificial muscles in the form of braces, sleeves and orthotic devices to enhance mobility for elderly (disabled/injured) people has increased due to an aging society. While traditional assistive devices used motors/gears, recent advances in materials science, sensing and actuation provide exciting opportunities to integrate and create truly innovative and multifunctional assistive devices. Despite these advancements, the development of assistive devices is facing various challenges such as designing and placing actuators, sensing external disturbances and most importantly, controlling the structure of these systems with respect to the highly contrasting environmental, operational, performance specificities and safety requirements. Because human motion is inherently dynamic and given the manifest complexities in designing assistive devices, the proposed pilot project will provide the first step towards quantifying the dynamics to provide design insight into modifications or specific treatment goals.

Technology: A manikin arm is instrumented with flexible pressure sensors and a Kevlar sleeve is integrated with the system. The entire setup is tested in a mechanical load frame to evaluate the pressure applied by the Kevlar sleeve on the manikin arm. A finite element model is also created using the software LS-DYNA and experiments conducted to validate the model. When completed, the system will include a well-characterized manikin arm along with a mechanistic simulation/modeling environment and also include the physical components with details for the unique fabric-sensing approach.

PI: Dr. Michael Keefe – keefe@udel.edu; Collaborator: Erik Thostenson – thosten@udel.edu

Aims: 1. Characterize force transmission of synthetic tendon configurations 2. Optimize actuator properties and insertion points to maximize functional utility 3. Evaluate physiological effect of exosuit on arm

Motivation: Each year, 795,000 people suffer a stroke in the United States. A major complication of stroke is hemiparesis, which inhibits the ability to perform activities of daily living. Wearable and practical for daily living, an exosuit is a device designed to help people with disabilities such as these by providing mechanical support to compensate for diminished muscular capacity. Exosuits that target the shoulder are often designed to provide support for the arm against gravity, the largest force that the arm must regularly overcome. Many exosuits have used tendon-driven actuation to assist the arm against gravity. These exosuits have shown the ability to alleviate muscular demand through soft and lightweight actuation. However, it is not known how the placement and lines of action of force-providing tendons impact the kinematics and physiological response of the user. The objective of this project is to characterize the mechanics of human-exosuit interaction, which will drive the development of a tendon-driven exosuit for assisting shoulder motions.

PI: Dr. Jill Higginson – higginson@udel.edu

Aims: 1. Synthesis of conductive polymers with redox active crosslinks for reversible crosslinking under a voltage 2. Characterization of the mechanically adaptive materials and integration in stretchable fabric 3. Development of a wearable assistive prototype for robotic-assisted motion

Motivation: Until recently, motion in soft robotic devices relied mainly on pneumatic actuation. Shape-memory and stimuli-responsive polymers provide lightweight and conformable alternatives to pneumatics. These materials enable new possibilities and applications in wearable actuators and soft robotics for seamless human–machine interfaces. However, the adoption of these materials has been hampered by inadequate choices of stimuli to actuate devices. Currently, dynamic responses in the mechanical properties of these materials can be triggered thermally (slow, non-specific, and often incompatible with biological systems), chemically (incompatible with biological systems and impractical for device integration) or photochemically (limited by the depth of light penetration and the use of biologically damaging UV radiation). To address these limitations, we are developing new conductive materials that can modulate their mechanical properties using an electrical stimulus (at low voltage).

Technology: We are synthesizing conductive polymer composites functionalized with iron (Fe) crosslinkers. Fe(III) provides a reversible crosslink: when Fe(III) is reduced to Fe(II), it weakens the metal-ligand coordination, which reduces the extent of crosslinking. By applying a negative voltage, the material “softens” and conversely “hardens” under a positive voltage. Such a redox cycle is reversible and easily controlled. The presence of conductive polymers allows for rapid charge transport to the metal crosslinkers. These new materials will be integrated in functional garments and assistive devices.

PI: Dr. Laure V. Kayser – lkayser@udel.edu

Schematic of the conductive composites with reversible crosslinking and mechanical properties

Aims: 1. Achieve new LFP and LTO fiber electrodes directly made with solid polymer electrolytes 2. Achieve an all-solid-state fiber lithium ion battery with useful charge-discharge rates and cyclability 3. Deliver a fabric swatch integrated with the all-solid-state fiber batteries with functional performance

Motivation: Wearable electronic devices represent a paradigm change in consumer electronics, on-body sensing, artificial skins, and wearable communication and entertainment. Fiber-shaped electronic devices, adopting 1D structure with small diameters from tens to hundreds of micrometers, have attracted broad interests for wearable electronic fields. Typically, fiber-shaped electronic devices are lightweight and flexible, and they can adapt to various deformations like bending, distortion, and stretching. More importantly, it is feasible to weave the fiber-shaped electronic devices into flexible, deformable, and breathable textiles that can facilitate practical applications.

Technology: In this project, we will apply the unique solid polymer electrolyte into the design and fabrication of fiber LIBs. The new fabrication process is as follows: the SSE (clear liquid before solidified) is mixed with cathode (LFP) or anode (LTO) powders and conductive additive CNTs to form a highly viscous paste; an 3D printer turns the paste into filaments, which are solidified by UV or thermal initiated crosslink polymerization reactions; the filaments are further coated with a thin layer of SSE by dip coating and UV solidification method, to form fiber electrodes; the fiber electrodes are twisted together and encapsulated by a UV-curable polyurethane coating to make a fiber lithium ion battery. The fiber LIBs are then integrated into the fabrics according to the needs. In this process, the SSE not only replaces the liquid or gel electrolyte for the fiber cell assembly, but also replaces PVDF to be the support matrix of the bulk fibers. The benefits are: (1) overcome the leakage and safety concern; (2) increase ion transport conductivity inside the fibers; (3) reduce the deadweight of inactive materials and therefore increase cell energy density; and (4) simplify the fabrication process. This will be the first all-solid-state fiber lithium ion battery, which has never been reported previously.

PI: Dr. Kun Fu, kfu@udel.edu