ZERO Brush — Design Thinking Case Study

Shubham Som Gupta
Jul 4, 2020 · 7 min read

Pooja Doshi, Anna Abraham, Raj Vichare, Shubham Som Gupta

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The beginning of this winding journey is where most design thinkers start — a wicked problem. As 4 metro city students, waste was part of the city landscape that had become a part and parcel of Mumbai’s maximum city experience whether spilling from the festering dumpster down the street or decorating the footpath under our feet.

Digging through the Waste

To understand this problem better we set out to observe and interview the stakeholders involved in the stages of processing garbage. We shadowed campus cleaning staff, spoke to garbage collectors and tried to dissect the problem, find the area of intervention and to transpire a feasible solution.

Stakeholder Map
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Dialogue with Cleaning Staff

“We don’t like to touch the kachra (Hindi for Garbage) but we have no choice” -Cleaning staff

Document Research

Online content and secondary research helped us in understanding a bigger picture. The contents studied were dumped on a mind map, which consolidated the what’s, when’s, where and how’s of “garbage”. Of everything on the mind map, one that stood out was plastic waste and its effect on environment.

Brainstorming, Mind Map & Affinity Mapping

Clogged drains in Mumbai monsoons are a common phenomenon because of single use plastic. But, what is a year round problem is actually another subset of plastic waste that produces over 50 millions pounds of waste every year — the toothbrush!

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Did you know that every toothbrush ever created since its making in the 1940s still exists somewhere on earth ?

That’s because the plastic takes 400 years to decompose! Not only that, but even the manufacturing of the nylon bristles produces greenhouse gases that are 310 times more potent than carbon dioxide.

Primary Research

Alongside our secondary research, we started interviewing people across different demographics to understand their

  • Brushing habits
  • Buying Preferences
  • Importance of oral hygiene
  • Knowledge of SUPs (single use plastics) and it’s relationship with toothbrushes
  • Price sensitivity to eco-friendly products.

“I want my kid to brush twice a day, but I don’t do it myself.” — Susan, Homemaker & Mother

“Sustainability is important to me, but I don’t know how to contribute to it.” — Dhruv, Outstation Student

“Colgate ka sasta waala toothbrush dedo bhaiya” [Translation: Brother, give me a cheap Colgate toothbrush.] — Manoj Bhai, Grocery Store Owner

The 3 important findings were:

  1. A majority of people knew that brushing twice a day was important but could never make the habit- This identified a need of the consumer.
  2. Replacement of toothbrushes was only done when the brushes lost their shape and not out of concern for oral hygiene — this identified another need of the consumer.
  3. People were aware of plastic pollution but had no idea that toothbrushes were a large part of that problem. — this identified a sensitivity to the problem that we were solutioning.

These findings were specifically useful because we knew that just solving the waste problem caused by the toothbrush wouldn’t cut it. We had to offer the consumers something greater for them to switch habits in our favor.

This helped us narrow down to our problem statement:

“How might we create a sustainable product that encourages better oral hygiene habits amongst its users?”


In this stage, we put up our HMW statement in focus, and all empathy map, emotion-function matrix, on the sides to give us a clear picture of the problem that we had solved. This helps us with not deviating from the problem statement while converging and diverging in the process.

During the ideation phase, each member brainstormed on many ideas in the multiples of hundreds. Considering no idea is bad, each idea was weighed upon, thought, and screened. Four ideas were selected from the list of top sorted ideas from the Idea Dump which is given below. We then used the DVF framework to further converge on ideas which are best suited.

Idea Dump
DVF Framework
Ideation Sketches


Our prototyping can be broadly categorized into two main sessions:

Session 1 was a series of fast and dirty prototypes during the ideation phase to help boil down the ideas and help us select the final concept of the product. It involved a detachable head, that would be eventually made from a sustainable material. We also wanted to user to have fun while doing a mundane act of brushing and voila — we have toothpaste pellets.

Crude Prototypes

Session 2 was a series of prototypes of the final idea making iterations as in when we got feedback from the users. We also realized during the prototyping, that we could with toothpaste pellets, encourage the user to brush twice — once in a day, once at night.

3D Printed Prototype

User Testing

The two main points of feedback we got from users were -

  • The detachable head was not as stable as a regular toothbrush.
  • Slide mechanism on the pellet dispenser on the body of the product was flimsy.
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Working of product

The toothbrush is made up of multiple materials.

The head of the toothbrush is made up of bamboo, and the bristles are made of a combination of Hemp and Nylon (4%), which makes it almost sustainable. The bristles deform in 2–3 months, thus compelling the user change the head in such time, which makes it replaceable.

The brush body is made up of recyclable plastic. Since it’s the main part of the brush, it is not to be replaced after every few months, its time of shelf time increase, thus positively impacting the environment. The body of the brush has a tray and slider, which gives access to the toothpaste pills, which nudge the user to brush twice a day. This feature makes it trackable.

The tray contains two sections, i.e. one for the day and another for the night. The day section will contain Mint flavored toothpaste pills, that will give a sense of freshness in the morning. In the night, the user uses the Chamomile flavored toothpaste pills that keep the user relaxed before sleeping, because of its soothing nature.

The user gets two flavors to brush with, thus encouraging a habit to brush twice a day. This makes it Incentivizing.

To make a behavioral change in the user, an added nudge is also given when the user just brushes in the morning. The morning section goes empty, but the full section of night pills nudges the user to brush in the night.

Nudge is a concept in behavioral economics, political theory, and behavioral sciences which proposes positive reinforcement and indirect suggestions as ways to influence the behavior and decision making of groups or individuals.

The greatest threat to our planet is the belief that someone else will save it.

This project was an eye opener to the world of sustainability. Not only did it force us to think out of the box but also educated us to be better designers, one’s that designed with the intention to create with least possible environmental impact.

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