top of page

Cooling Clips

Product Design, Design Thinking, Rapid Prototyping
ROLE
Project Manager
TEAM
Ami Sao
Ananya Chatterjee
Calvin Kennedy
Sean Lim
TIMELINE
September-December 2022 
(Semester-long)
TOOLS
SolidWorks
Qualtrics
Raspberry Pi
3D Printers
DESCRIPTION
Semester-long project for my Human Factors Product Design course where we worked with a client to bring their product concept to life
IMG_2154.jpg
OVERVIEW
OBJECTIVE

To create a personal wearable passive cooling solution that users can easily install on their clothing that meets the specifications of our client

DELIVERABLES
High-fidelity prototypes and presentation to report our design process
CHALLENGES
Limited access to our intended user base for user testing/user research, lack of warm weather to test the effectiveness of our prototypes
OUTCOME + IMPACT
Developed three iterations of high-fidelity prototypes that effectively cool users for further development by our client
INTRODUCTION
CLIENT PROFILE
jintri01.png
James Intriligator:

  • James Intriligator is a professor in Human Factors Engineering and the Director of Strategic Innovation at Tufts University

  • Presented us with a "trouser chimney" concept as a means of passively cooling the user

  • Concept based on his own experiences with discomfort from being too hot which he attributed to excess heat trapped in his pants

  • "Trouser chimney" concept consists of a device installed between the user's hip and trouser to create a venting mechanism to allow heat to escape

INITIAL CONCEPT

Based on our client's specifications, we crafted our initial sketches and CAD model.

Rectangle 28InitialSketch.png
initialCAD.png

GOALS

  • Create a personal wearable cooling solution that users can install on their clothing with an emphasis on cooling the lower body

  • Provide an intuitive, portable cooling solution for users to enhance their physical comfort and minimize health risks from excessive heat

  • Formulate an effective passive cooling system that requires minimal user input to operate

  • Design a discreet cooling solution for users who are unable to utilize other established cooling strategies

MOTIVATIONS

  • The advent of climate change has brought about an increased incidence of heat-related ailments and deaths from the increasing global temperatures

  • Individuals with existing health conditions such as heart disease or obesity regulate body temperature poorly

  • Many individuals are unable to adapt to increased temperatures because of extenuating circumstances (social expectations, dress codes, etc.)

LIMITATIONS

  • User safety

  • Product must be intuitive so users aren't likely to misuse the product and cause harm 

  • Product size should fit most users of all body types

  • Must feature a passive cooling system that doesn't require any user or external input

RESEARCH

PERSONAS

In order to better understand our potential user base and to help guide our user research, we crafted two personas: Office Oliver and Construction Carla. 

Office Oliver

BACKGROUND
  • From Hartford, CT
  • Accountant at a small insurance firm
  • 60 years old, hoping to retire
  • Has diabetes and low blood pressure
  • Lives alone with infrequent check-ins from extended family
DAILY ACTIVITIES
  • Commutes to work in poorly ventilated public transportation
  • Exercises before work to stay fit and combat long hours of sitting
  • Cooks healthy meals for himself
GOALS
  • Take responsibility for his health as he ages
  • Seamless and comfortable finish to the last few years of work
  • Save money for retirement
OfficeOliver.png
CHALLENGES
  • Exhausted from long 9-5 shifts
  • Suffers from heat exhaustion in the restrictive business casual attire
  • Unable to maintain clothing cleanliness as his formal attire often becomes sweaty and soiled
  • Becomes antsy when physically uncomfortable at work
  • Often finds himself overheating from his various health conditions

Construction Carla

BACKGROUND
  • From Houston, TX
  • Construction manager for 4 different housing projects
  • 32 years old
  • Mother of 2 young children
  • Leader for women in STEM groups
GOALS
  • Set the standard as the manager for the 100 people working in her branch
  • Be respected and supported as a fair manager that prioritizes the health and safety for her workers
CHALLENGES
constructioncarla.png
  • Has restricted movement and discomfort in her safety equipment and uniform
  • Tireless days running around in the heat from one project site to the next
  • Workers complain about poor work conditions due to heat and clothing discomfort
DAILY ACTIVITIES
  • School pickup, cooking dinner, and running family errands
  • Spends her days outside overseeing construction sites under the Houston sun

From our personas, new questions were raised:

  • How might we reduce discomfort due to heat, specifically in the pant region, for our customers?

  • How do we have a solution that is discreet and is adaptable to a wide array of workplace fashion?

  • How can we allow for a large range of motion associated with manual labor and comfort for sitting in place (office jobs)?

MARKET RESEARCH

We conducted market research for other clothing-based cooling devices to understand the current market for cooling devices and how our cooling clips will solve an issue not already addressed by existing products. 

Air Conditioned Pants

  • Creates an electric ventilation system for air

  • Portable but can only be used in specific pants

  • Bulky, reduces mobility, potentially loud, some may perceive as unsightly

  • Adjustable settings

Rectangle 16.png

Moisture Wicking Fabric

  • Not an add-on product (pants must be made from this material in order for it to function)

  • Light material that is comfortable to wear

  • No adjustable settings

  • Passive cooling system

Rectangle 18.png

Ventilation Pockets

  • Does not restrict movement and is comfortable

  • Makes use of passive cooling but is adjustable

  • Built in system, you can’t move it from one pair of pants to another

Rectangle 17.png

MIT Synthesized Gel

  • Imitates camel fur by keeping out external heat but allowing for vapor to pass through

  • Two layer passive cooling system (aerogel and hydrogel)

  • Has only been used to keep foods cool so far

Rectangle 19.png

PASSIVE COOLING SYSTEMS

To better understand cooling mechanisms, we researched passive cooling systems in architecture. 

  • Passive cooling systems use natural air movement to let cool air in and move hot air out

In the context of cooling clips:

  • Air movement can come from natural leg movements of the user

  • There is much less space inside a user's pant leg to allow for special air movement

  • Pant material is much less insulating than walls of a building so more heat can naturally escape through the pant

Malqaf.svg.png

TWO-POINT SENSITIVITY

Since our cooling clip will be nestled between the user's hip and their waistband, we researched two-point sensitivity as a means to gauge the comfort level at that touchpoint.

Definition: 

Two-point sensitivity refers to the ability to discern that two nearby objects touching the skin are two distinct points. Two-point sensitivity values indicate the distance at which two points begin to be perceived as one—the lower the two-point sensitivity value, the more innervated/sensitive the body part. By comparing two-point sensitivity values, we are able to tell how finely innervated/sensitive an area of skin is.

Findings:

  • Two-point discrimination values of the lower back and upper thigh range from 313-315 mm while that of other parts of the lower limb range from 206-304mm

  • Two-point sensitivity values indicate that the tactile sensitivity of the waist is lower than other parts of the lower body 

Based on two-point sensitivity values, wearing a cooling clip at the waist won't create excess discomfort.

TASK ANALYSES

In order to better understand existing methods/techniques users implement to cool themselves and the cognition behind them, we conducted two task analyses with Athletic Angela and Healthy Henry where they were put in situations where they might experience discomfort from excessive heat.

Athletic Angela

We observed Athletic Angela run on the treadmill for 10 minutes while narrating the cognition behind the actions she took to cool herself. 

Rectangle 42.png

Behavior During Run

Cognition (During Run)

Tells us she feels hot

Continues jogging at a steady pace because she’s not hot enough to take action

Tells us beads of sweat are forming on her forehead, back, and "kneepits"

Continues jogging at a steady pace because she’s not hot enough to take action

Removes sweatshirt

Her back is hot and by removing the extra layer she hopes to reduce the amount of heat by her back

Wiping forehead sweat

The sweat is wet and uncomfortable, she also does not want it to fall into her eyes while shes running so she wipes it away using her hand 

Behavior Post Run

Cognition (Post Run)

Wipes sweat from face

Removes the beads of sweat that are wet and uncomfortable

Paces

"Kneepits" and back of thighs are warm and increased airflow helps cool it down, lowers heart rate to cool oneself

Seeks hydration

Drinking water will help with recovery from the run 

Moves fabric of pants 

Indicates her legs are warm

Splashes water on face

Washes sweat off face, lowers perceived warmth

Takes off sweatpants and changes into shorts

Removes the excess layer that is insulating her body heat, increases ventilation to lower body

Healthy Henry

We observed Healthy Henry's actions after a 15-minute game of squash while he narrated the cognition behind the actions he took to cool himself. 

Rectangle 43.png

Behavior Post Run

Cognition (Post Run)

Paces

Increases airflow to decrease perceived warmth, lowers heart rate to recover from exertion

Takes off hat and runs hands through hair

Hair was getting sweaty so wanted to let it breath/dry so it would be less sweaty and uncomfortable

Seeks hydration

Drinking water will help with recovery from exercise, cools body

Fluttering his shirt to let air out

Rapidly ventilates air around body by getting the hot air out and cooler air in, fans body

Findings

  • Heat felt most intensely after physical activity

  • Both personas sought hydration immediately after exercising

  • Both of our personas paced after their exercise and used techniques to maximize airflow to their bodies

  • Interaction with water (face washing) was perceived as an effective cooling mechanism 

QUESTIONNAIRE

Upon conversations with our client about his experiences as well as some initial research into established/proven strategies to cool oneself, we crafted a Qualtrics questionnaire in order to better understand our user base and the ways they experience heat.

Goals

  • Better understand when users experience discomfort from heat

  • Determine user's style habits and how clothing choice relates to discomfort from excess heat

  • Identify the strategies potential users already implement to cool themselves and verify the effectiveness of each

Rationale

  • To determine the situations, both environmental and at a personal level with clothing choice, in which a cooling clip might be most useful

  • To identify the cooling mechanisms our users find the most effective in order to implement those strategies into the design of our cooling clips

Findings

  • Discomfort related to heat most often experienced outdoors in summer and outdoors in winter

  • 91% of users agree that weather influences what they wear

  • 64% of users believe that work and social expectations prevent dressing for the weather

  • Although denim and polyester are the most common materials worn, they are deemed the most uncomfortable by users

EXPERT INTERVIEWS

To help guide our design process, we conducted expert interviews to better inform our prototyping process for user comfort and ventilation efficacy. 

dhanno02.jpeg

Daniel Hannon

Professor of Human Factors Engineering at Tufts University

Insights

  • Anthropometric measurements for women and men may differ. How might we design to make cooling clips work for all body types?

  • Odor of air inside pants is a possible concern

  • Model ventilation mechanism after passive cooling systems in architecture

  • Other potential customer bases: Members of the army

Rectangle 20.png

Marc Hodes

Professor of Thermodynamics at Tufts University

Insights

  • Viewing the pant leg as a heat tunnel can allow for the application of a heat equation to find the heat flow out of the pant based on gap created by the cooling clip

  • Heat input = body radiation, heat output = flow through gap + radiation through pant material 

  • However, this model would be very assumption heavy. It assumes a uniform shape without considering knees, muscle definition, or leg shape changes from walking

PROTOTYPING

NEEDS + REQUIREMENTS

Based on our research phase, we translated user needs into requirements for our product. 

User Needs

User Requirements

User needs to be comfortable / not sense the device while wearing it.

Device should be designed to be worn in a low-sensitivity area (e.g., lower waist area) to minimize pain or discomfort caused to user

Physical shape of the device should ergonomically fit the curvature of a generic waist

Device should be flexible and not obstruct natural bodily movements or exceed anatomical constraints

The device needs to be easily installed and removed

The device should have minimal interactive parts to avoid confusing the user

The clipping mechanism of the device should be easily maneuverable by all users

The device needs to work with multiple kinds of pant designs and materials

Device should be physically malleable to fit on a broad range of pant shapes and thicknesses

The device should not attract additional unwanted attention to the user

Device, when worn, should be as invisible as possible to third parties

The device needs to remain wearable and comfortable during motions of various intensities

Device should emphasize dynamic wearability and have a tight clasping mechanism to ensure it does not fall off during motion

The device should not obstruct comfortable movement when worn during intense physical activity

The device should be relatively resistant to damage or deformation

Material of the device should be durable and resistant to wear by bending or friction

The device should be able to be used by users of different body types and sizes

Device should have adjustable dimensions to be comfortably worn by users with different anatomical constraints

User should find the device’s aesthetic to be ubiquitous

Device should not have overly eye-catching or unconventional aesthetics which could dissuade usage

An assortment of colors could be provided to allow device to blend into different garments of clothing

User should be able to wear device without damaging their clothing

Design of device should have rounded smooth edges to minimize the chance for any tearing or stretching of clothing

IDEATION

Screen Shot 2022-12-19 at 2.20 1.png

With our needs and requirements in mind, as well as guidance from our client, we sketched possible design ideas for our cooling clips

Crescent

Matches curve of hip for comfort

Circular

It's impossible to design a universal hip curvature for all users, so a circle could be a universal alternative that's comfortable for all users

Short Length

Matches the industry standard for trouser waistbands

Clip

Secures product to trouser waistband

ITERATION 1

Crescent

CoolingClipLongCrescent.png

Long

CoolingClipShortCrescent.png

Short

Circular

CoolingClipLongTube.png

Long

CoolingClipShortTube.png

Short

IMG_2139 1.png

3D Printed CAD models with PLA (Polylactic Acid thermoplastic)

USER TESTING

In order to collect feedback on customer satisfaction and cooling efficacy for these prototypes, we conducted a test for each: a customer satisfaction questionnaire and an efficacy experiment. 

Customer Satisfaction Questionnaire 

Assesses the perceived user satisfaction from these four prototypes

Screen Shot 2022-12-18 at 2.59 1.png

Questions include: 

  • Likert Scale for efficacy, ease of use, comfort, and style

  • Alignment to user needs

  • Value Proposition:

    • ​“Please rank the features of the cooling clip that are most important to you”

  • Subjective evaluations

  • Open-Ended Feedback:

    • “If you could change just one thing about the clip, what would it be?”

Results:

  • User Persona:

    • 54-year-old male who tried all 4 clip prototypes ​in various locations and combinations with sweatpants during a workout

  • Favorite clip was short crescent

  • Somewhat satisfied with the overall product

  • Most important feature is a small and portable product

  • Described clip as "useful," "effective," "valuable," and "easy to use"

  • Perceived a "difference in overall hotness and overall sweatiness"

Key Takeaways:

  • The 1st iteration of cooling clips successfully addressed their purpose of alleviating perceived heat-related discomfort in the lower body; however, revisions are needed to increase user-friendliness.

  • Experiment with the clip positioning (ankle vs hip) and quantity

  • Wider dimensions of the clip so it can apply to lower-back area
    (e.g. 4 inches wide, 1 inch deep, and a 0.8 cm opening)

  • Explore materials more flexible to movement (ex. fabric, flexible plastic)

Efficacy Experiment

To test the effectiveness of our cooling clip prototypes, we devised an experimental setup to quantitatively determine if a venting mechanism like the one utilized in our cooling clip prototypes effectively cools the user. 

Experimental Setup:

  • Use of a hot water bottle to simulate a human leg emanating body heat

  • Wrapped water bottle in fabric to simulate pant material surrounding a leg

  • Held temperature sensor between the water bottle and the leg 

  • Temperature was recorded for ~4 minutes as this was around when temperatures stabilized

  • Control: Plain experimental setup

IMG_8542 1.png

  • Variant: Ring held between the bottle and the wrapping fabric to emulate the venting mechanism of the cooling clip

IMG_8549 1.png

Results:

  • Control experiment set-up recorded a far quicker rise in ambient temperatures, with temperatures stabilizing at around 113 degrees

  • Variant experiment set-up recorded a more gradual rise in ambient temperatures, with temperatures stabilizing at around 92 degrees

Rectangle 15.png

Conclusion:

Data tells us that the wearing of a cooling clip between legs and pant fabric could facilitate the removal of excessive lower body heat

ITERATION 2

Based on the feedback from Iteration 1, new prototypes were developed for the second iteration. 

CoolingClipJamesIteration 1.png

Alterations:

  • Altered crescent shape to fit the lower back region

    • 4 inches wide, 1 inch deep, with a 0.8 cm opening

  • Thinner (2mm) walls to decrease weight and clunkiness

  • Flexible material for comfort and to match the movement of the user

The "Long Crescent" design from Iteration 1 was also printed with these new materials to see if the material improved the Iteration 1 design

IMG_2142 1.png

Less rigid ABS

(Acrylonitrile butadiene styrene)

IMG_2149 1.png

Very flexible TPU (Thermoplastic Polyurethane)

FUTURE STEPS

  • User testing of the new prototypes

  • Add hinges at the clip-tube joint for mobility so that the venting tube inside the pant can move with the body while the clip can stay attached to the waistband

  • Experiment with more comfortable materials like fabric

  • Conduct wider testing to get more feedback from a wider audience

  • More in-depth efficacy tests, ideally including testing with real users

  • Bring to market strategy: branding, manufacturing, patenting/licensing

bottom of page