Portfolio · Student engineer
I'm Yatharth. I'm 14 and I'm passionate about turning ideas into real, working things. I design my own parts, wire my own circuits and keep testing until it works.
I want to become an engineer who makes useful technology affordable for everyone. This project is a good example: clean air shouldn't cost ₹40,000.
See my air purifier ↓Featured project
1The issue
Air pollution is one of India's biggest health problems, and we breathe most of it indoors at home and at school. Air purifiers help, but a good one costs more than many families can spend.
people in India died in 2022 from exposure to fine particle (PM2.5) pollution, according to the Lancet Countdown report.
India's average PM2.5 level in 2024 was about 50.6 µg/m³, roughly ten times the WHO guideline of 5 µg/m³.
is what branded air purifiers cost in India today, from an entry-level Xiaomi up to Dyson's top model.
Sources: Lancet Countdown 2025 figures for India · prices from MySmartPrice and Smartprix, October 2026.
2My solution
In any air purifier, the part that actually cleans the air is the filter. The rest is a fan and a housing. So I bought a real HEPA + carbon filter and a proper fan, and designed and 3D printed everything else myself.
Exploded schematic: every part stacks on one centre line.
3My mechanics
The purifier works in three stages: suction, filtering and Coanda-assisted spreading. Scroll down to the 3D walkthrough to watch the airflow.
The 13 W fan at the top pushes air out of the cap. That lowers the pressure inside the hollow core of the filter, so room air rushes in from all sides to fill the gap.
The fine mesh stops hair and lint. The pleated HEPA layer traps fine dust, pollen and smoke particles. The carbon layer absorbs smells. Only clean air reaches the core.
Clean air leaves through the grille, follows the curved rim of the cap, and spreads outward across the room instead of only going straight up.
The Coanda effect is when a fast-moving stream of air bends to follow a curved surface next to it, instead of flying off in a straight line. Dyson builds its whole bladeless fans and purifiers around this. They shoot a thin jet of air over a carefully shaped curved surface, and that jet drags extra room air along with it (this is called entrainment).
My cap does the same thing in a simpler way. The air coming out near the edge of the grille hugs the rounded rim of the cap and turns outward. That gives two benefits. First, clean air is spread around the room instead of only hitting the ceiling. Second, the moving air pulls more room air into circulation, which helps mix the whole room.
Safety plus Coanda: Dyson hides its fan inside the base to make the outlet "bladeless." My fan is fully enclosed inside the printed cap, behind a grille with small holes, so fingers can't reach the blades either.
Air hugging the curved rim (green) and pulling surrounding room air along (grey).
3D walkthrough · start
A 3D model of my purifier. Keep scrolling: it splits into its six parts one at a time, then shows how dirty air goes in and clean air comes out. Move your pointer to tilt it.
Exploded view · part 1 of 6
A flat ring on three cone-shaped feet. Three feet always sit flat, so the tower never wobbles. It lifts the filter off the floor, and its centre opening lines up with the filter core.
Exploded view · part 2 of 6
The heart of the purifier. Dirty air passes through the pleated HEPA wall from outside to inside, which traps fine dust, pollen and smoke. Then the dark activated-carbon layer absorbs smells.
Exploded view · part 3 of 6
A thin stepped ring that sits on the filter's top end cap. It closes the gap between the filter and the collar, so air can't sneak around the filter without being cleaned.
Exploded view · part 4 of 6
A tall ring that joins the round filter to the fan cap. It leaves space above the filter so the blades spin freely, and its inner ledge holds the cap at the right height.
Exploded view · part 5 of 6
A 5-blade 230 V fan (PN EAA42HB503). It pushes air out of the top, which lowers the pressure inside the filter core and pulls room air in through the filter.
Exploded view · part 6 of 6
Holds the fan with two screws. Its perforated top lets clean air out while keeping fingers away from the blades, and its rounded rim helps the air spread across the room (Coanda effect).
3D walkthrough · airflow
Dirty air (orange) is pulled in from every side. Dust gets trapped on the filter (brown dots). Clean air (green) rises up the core, leaves through the grille and follows the curved rim outward into the room.
3D walkthrough · pre-filter
With the fine mesh wrapped on, the big particles like lint and hair stop at the mesh before they reach the HEPA pleats. The filter stays clean for longer.
4Schematics
The electrical side is kept as simple as possible: the fan connects straight to 230 V mains. Fewer parts means fewer things that can fail.
Cross-section: dusty air in from all sides (orange), clean air up the core and out over the rim (green).
5Comparison
Branded purifiers use the same basic idea as mine: a fan pulls air through a HEPA + carbon filter. What you pay extra for is mostly sensors, app control, design and the brand name.
| Purifier | Price (₹) | Filter | Air intake | Airflow trick | Clean-air rate | Extras | Costs |
|---|---|---|---|---|---|---|---|
| My purifierDIY, 2026 | 2,000 | HEPA + carbon, + washable mesh | 360° tower | Coanda-assisted curved rim | Not lab-tested yet | Repairable, printable parts | 1× |
| Xiaomi Smart Air Purifier 4 Lite | 10,990 | HEPA + carbon | 360° tower | Standard fan | 360 m³/h | App, sensor, display | 5.5× |
| Philips AC1715/60 | 15,999 | HEPA + carbon | Front / sides | Standard fan | 300 m³/h · 27 W | App, sensor | 8× |
| Dyson Purifier Cool TP07 | 41,000 | HEPA + carbon | 360° base | Air Multiplier (Coanda) | Not given as CADR | Fan mode, app, sensors | 20× |
| Dyson Purifier Big+Quiet BP02 | 68,900 | HEPA + carbon | 360° | Cone-shaped Coanda projection | Not given as CADR | Large rooms, app, sensors | 34× |
Prices are the lowest listed in India in October 2026 and change often: Dyson (MySmartPrice), Xiaomi (Smartprix), Philips (official site). How Dyson uses the Coanda effect: TechRadar. My purifier's clean-air rate hasn't been measured with lab equipment yet. That's my next test.
6Money
saved compared with a Dyson Purifier Cool TP07 (₹41,000).
a month to run 8 hours a day: 13 W × 8 h × 30 days ≈ 3.1 kWh, at about ₹8 per unit.
for a replacement filter. Everything else can be reused, and the mesh is washable.
proprietary parts. If something breaks, I can print it again.
7Safety
The fan runs on 230 V mains, so I treated safety as part of the design, not something added at the end.
The blades sit inside the printed cap behind a grille with small holes, so fingers can't reach them.
The printed parts and the filter don't conduct electricity, so the outside of the purifier is not live.
The fan uses only 13 W (about 0.06 A), so very little heat builds up near the plastic parts.
Three feet always sit flat, even on uneven floors, and keep the tower from wobbling or tipping.
Brown live and blue neutral follow the standard colour code. Every joint goes in an insulated connector, with no bare copper.
The filter and mesh are changed only with the plug out. The cap lifts off without tools.
8Advantages
Same type of HEPA + carbon filter as purifiers that cost ₹11,000 to ₹69,000.
Air is pulled in through the whole filter wall, so the full filter surface is used.
Uses less electricity than a bulb and costs about ₹25 a month to run.
The curved rim spreads clean air across the room, the same physics Dyson uses.
The fine-mesh pre-filter takes the big dirt, so the expensive filter clogs more slowly.
Every printed part can be reprinted or improved. Nothing is locked to one brand.
9The parts
The full photos of my build, with each feature pointed out. The white parts are 3D printed. The filter and the fan are bought parts.
A flat printed ring standing on three cone-shaped feet. The filter sits on top of it.
A round replacement purifier filter. Air passes through its wall from the outside in.
A thin ring with a step on the inside. It sits on the filter's top end cap.
A tall printed ring with a ledge inside. It is the adapter between the filter and the fan cap.
Seen from underneath: the fan is screwed inside the printed cap, with the blades facing down into the filter.
A sheet of fine mesh wrapped around the outside of the filter, from the base up to the seal ring.
10Build it
| # | Part | Qty | Type / spec | Cost (₹) |
|---|---|---|---|---|
| 01 | Base ring with 3 cone feet | 1 | 3D printed | 500 (all printing) |
| 03 | Seal ring | 1 | 3D printed, stepped | |
| 04 | Collar | 1 | 3D printed, inner ledge | |
| 06 | Fan cap with grille | 1 | 3D printed, curved rim | |
| 02 | HEPA + carbon filter | 1 | Cylindrical replacement filter | 1,000 |
| 05 | AC fan | 1 | 230 V · 13 W · 50/60 Hz | 500 |
| 07 | Fine mesh | 1 | Fabric or nylon mesh | — |
| 08 | Cable, plug, screws | 1 set | 2-core cable, 3-pin plug, 2 screws | — |
Print the base, seal ring, collar and fan cap. Clean off stringing and rough edges so the rings fit snugly.
Place the fan inside the cap with the blades facing the open side. Fix it with two screws through the grille and pass the wires out through the top.
Spin the blades by hand. They must not touch the cap wall anywhere.
Stand the base on its three feet and lower the filter onto it, centred over the opening.
Press the seal ring onto the filter's top cap, then slide the collar over it. There should be no gap you can see light through.
Drop the cap into the collar until it rests on the inner ledge. Now air can only reach the fan by going through the filter.
Cut the mesh to the visible filter height, wrap it once with a small overlap, tuck the edges under the seal ring and onto the base, and close the seam with Velcro or stitching.
Keep it smooth and single-layer. Bunched mesh blocks airflow.
Brown to live, blue to neutral, every joint insulated. Plug in: you should feel air leaving over the rim and being pulled in at the sides.