BagPost

How it fits together

BagPost, 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

Real-time 3D render · drag to rotate · final design may varySwipe sideways to rotate

1. 01

   The whole BagPost

   A stand weighs the hanging night drainage bag. It logs each emptying in mL and alerts the carer's phone when nothing is draining.

2. 02Brain

   Seeed XIAO ESP32-C3

   The brain: it runs the bagpost-head firmware program

3. 

   03

   5 kg load cell

   Weighs the bag to about 0.4 g

   Seeed XIAO ESP32-C3 · 4 wires to amplifier · Tiny bridge voltage

4. 04

   HX711 amplifier

   Turns the load cell signal into a 24-bit number

   Seeed XIAO ESP32-C3 · 2 GPIO pins (D0, D1) · Weight readings

5. 

   05

   12-LED light ring

   Shows fill level, amber for alerts, red if knocked

   Seeed XIAO ESP32-C3 · GPIO data line (D8) · LED colour data

6. 06

   CHECK button

   Acknowledges an alert, checks the bag and tares

   Seeed XIAO ESP32-C3 · GPIO pin (D10) · Button presses, wake signal

7. 

   07

   18650 cell + USB-C

   Runs the stand for about 58 days per charge

   Seeed XIAO ESP32-C3 · Board battery pads, USB-C charge · Power

8. 08

   All connected

   6 key parts, one program, and your phone

The idea

The night-bag stand and the bed-rail urinal hook weigh what is passed, so every room's output is logged in mL

How the parts connect

BagPost, 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 BagPost

while (true) {
  power_on(HX711_VCC);                    // switched by a P-FET from D2
  grams = hx711.read_avg(20);             // 2 s at 10 samples/s
  power_off(HX711_VCC);
  ring24h.push(grams);                    // 1-minute masses
  step = grams - ring24h.previous();
  state = state_machine(state, step);     // NO_BAG, HUNG, DRAINING, REMOVED
  if (alert_rules(state, ring24h, baseline))
    mqtt.publish("event", alert_json());  // NO_DRAIN, KNOCKED, EMPTIED
  if (ten_minutes_elapsed())
    mqtt.publish("status", status_json()); // g, mL, rate, battery
  show_ring(state);                       // D8 via P-FET
  deep_sleep(60 /*s*/, WAKE_ON_BUTTON);   // button on D10 wakes early
}

To your phone

How the data reaches BagPost carer phone and manager dashboard

Shared phone or browser

1. Stand head
2. Wi-Fi · MQTT over TLS
3. IEMI cloud
4. Phone alert · web dashboard
5. Carer and manager

Key specs

Targets for production units; they may change during development.

Pricing

Target pricing (£65 per RailHook, £129 per stand in the UK). Parts cost is about $47 per RailHook and $84 per stand at qty 1 (est.).

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

1. 28 Oct 2026, 14:25LatestA care home or ward needs catheter and urinal output logged in mL and a blocked catheter seen before the next round; ward output charts are correct only 21% of the time (Lim et al., BJN 2021) and 43% of long-term catheter users need out-of-hours care in a year (sources in DESIGN.md).

   • Drawn idea plan (idea.json): a care-home corridor at night with three residents' rooms, the night station and the sluice room; pins for a BagPost stand in two rooms and a RailHook on a bed rail
   • The product picture is now this drawn plan instead of the plain fallback card; drawn from the rev A and A1 design notes, not the CAD
   • BagPost monitors and alerts only; the carer still checks the person
   • Next: drawn plans for more catalogue products, then deeper market checks on the flagships

   See it in 3DFull research and design

2. 27 Oct 2026, 03:45Owner decision (27 Oct 2026): merge our single-job products into multi-job devices.

   • New product page: https://iemilabs.com/products/bedside/

   See it in 3DFull research and design

3. 25 Oct 2026, 23:49Ward nurses get urine output wrong far more than intake: in a 2,199-patient chart review, output was charted correctly only 21% of the time, and the commonest wrong entry was "void in toilet" with no amount (Lim et al., British Journal of Nursing, 2021).

   • New CAD parts: RailHook case that rides over a bed rail up to 30 mm, its lid, and a J-shaped bottle cradle; 21 bought parts fit-checked, lid on case 0 mm³
   • New CAD reports for void accuracy and how often to weigh (10 s reads, about a month per charge, est.)
   • BOM: about $47 per RailHook at qty 1 (est.)
   • Design doc: dated section on the ward fluid-chart need with 4 sources and 3 new tests
   • Product page: summary, problem, highlights, use cases, how it works, pricing and FAQs updated for the RailHook

   See it in 3DFull research and design

4. 25 Oct 2026, 10:28Blockage costs out-of-hours calls and A&E visits (43% and 15.5% of users a year) and first shows as no drainage → a 'no drainage for 2-3 h' alert against the person's own baseline, 5-6 h before an 8 h round (CAD flow report, est.)

   • New design: 4 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