OxyCart

How it fits together

OxyCart, part by part

Scroll or tap a part. Press “See the 3D CAD design” to watch the model, built from our CAD, light each part up and show how it connects.

See the 3D CAD designShow the concept

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1. 01

   The whole OxyCart

   An oxygen cylinder stands on a scale in a cart. The cart works out hours of oxygen left and alerts the family early.

2. 02Brain

   XIAO ESP32-C3 (cart)

   The brain: it runs the oxycart firmware program

3. 

   03

   Load cell + HX711

   Weighs the cylinder; the weight slope gives the flow

   XIAO ESP32-C3 (cart) · HX711 two-wire (GPIO) · Weight readings

4. 

   04

   Tilt sensor

   Ignores weight readings while the cart is moving or tilted

   XIAO ESP32-C3 (cart) · I²C (4 wires) · Tilt angle

5. 05

   CHECK / mute button

   Wakes the display or silences the beeper

   XIAO ESP32-C3 (cart) · GPIO pin · Button press

6. 

   06

   E-paper display

   Shows hours left; stays visible with no power

   XIAO ESP32-C3 (cart) · SPI · Screen image

7. 07

   FlowTee O2 sensor

   Measures oxygen purity and flow at the concentrator outlet

   XIAO ESP32-C3 · UART 3.3 V · Purity % and L/min

8. 

   08

   18650 battery

   Runs the cart for about 78 days per charge

   XIAO ESP32-C3 (cart) · Power lead via XIAO charger · 3.7 V power

9. 09

   All connected

   7 key parts, one program, and your phone

The idea

The backup oxygen cart, made smart: it weighs the cylinder, shows hours left and turns a power cut into a clear message

How the parts connect

OxyCart, wired up

Every part, what links it to the brain, and how the data reaches your phone. A solid line is a cable; a dashed line is a radio link.

The program

What controls OxyCart

while (1) {
    deep_sleep(60 s);                          // XIAO ~25 uA sleep
    w = hx711_read(2 s, 10 SPS);               // TAL220 load cell
    if (!still_and_level(lis3dh_read(), 1.0)) continue;   // tilt gate
    grams_left = w - cup_tare - cylinder_tare;
    flow = weight_slope(10 min);               // or the prescribed flow
    hours_left = (grams_left - reserve) / flow;
    if (due(10 min) || state_changed()) epaper_show(hours_left);
    if (due(10 min) || event())
        mqtt_publish("oxycart/<id>/cart", json(grams_left, flow, hours_left, batt_pct));
}

To your phone

How the data reaches OxyCart

Family phone and supplier alerts

1. Cart
2. Wi-Fi · MQTT over TLS
3. Cloud
4. App and push alerts
5. Family phone

Key specs

Targets for production units; they may change during development.

Pricing

Target pricing. DME fleet pricing on request. Parts cost is about $92 per cart and $83 per FlowTee at qty 1, about $175 for the kit (est.).

Indicative launch pricing in USD, excluding taxes and shipping. Final pricing is confirmed before any balance is charged.

1. 29 Oct 2026, 09:40LatestFamilies of people on long-term home oxygen read the backup cylinder's hours left off a psi gauge, and in a power cut the concentrator's buzzer says it stopped but not how long the cylinder will last; HHS emPOWER counted about 887,000 Medicare users relying on oxygen equipment in April 2023, and plain cylinder carts sell for $117 to $185 (OxyCart DESIGN.md market check).

   • Drawn idea plan (idea.json): a bedroom from above with the bed, the concentrator by the wall and its tubing, the backup cylinder on its cart, the socket and the router in the hall; pins for the weighing cart, the FlowTee on the concentrator outlet, the home router and the person on oxygen
   • The product picture is now this drawn plan instead of the plain fallback card; drawn from the design notes, not the CAD
   • What the plan keeps from the market work: it monitors and alerts only and never sets or switches the oxygen flow, and the power-cut alert works even when the router is down because both units going quiet together is the signal
   • Next: more drawn plans for catalogue products that still show the fallback card (parksense-ai, pesttrap-ai), then close-out C5 (buyer review prep for sports) from 12:00

   See it in 3DFull research and design

2. 27 Oct 2026, 11:45A patient on a gravity drip who also needs oxygen has a bag and a cylinder beside the bed that both run out. NHS England reviewed 120 oxygen cylinder incidents in 12 months, some with the cylinder empty at the point of use, and hospitals pay $78–189 plus a clamp up to $143 for holders that put the cylinder on the IV pole but tell nobody anything. Our own two products for it cost $448 and $10 a month a bed.

   • Combined into WardPole (https://iemilabs.com/products/wardpole/); OxyCart itself is unchanged

   See it in 3DFull research and design

3. 27 Oct 2026, 08:30Families looking after an older parent at a distance often face three worries at once: were the pills taken, how long will the backup oxygen last in a power cut, and is the parent still walking safely, especially on night toilet trips. Today that means a pill dispenser subscription (Hero $29.99-44.99 a month, herohealth.com), a medical alert ($25-29 a month, AARP 2026) and nothing for oxygen or walking; our own three products for it cost $447 and $14 a month with three apps.

   • Combined into ParentHome (https://iemilabs.com/products/parenthome/); OxyCart itself is unchanged

   See it in 3DFull research and design

4. 25 Oct 2026, 12:32People find cylinders empty only when breathless (MIJA case study) → the cart watches the weight all day and warns before the 200 psi reserve

   • New design: 6 printed parts in code CAD, bought parts fit-checked
   • Market research, hardware list and use case written up
   • Design page and kit render published
   • Product page added

   See it in 3DFull research and design