BagPost
The night-bag stand and the bed-rail urinal hook, made smart: they weigh what is passed and log output in mL
The 2 L night drainage bag hangs from a load cell at the top of the stand. BagPost knows the mL in the bag, logs each emptying with its volume as the output record, and alerts the carer's phone when nothing has drained since connection, when drainage stops for 2-3 h against the person's own baseline, when the bag is nearly full, leaking or knocked. The RailHook does the same for patients without a catheter: the urinal hangs on a bed-rail hook that weighs it, so every void is logged in mL instead of "void in toilet". It monitors and alerts only; it never touches the catheter and does not diagnose.
- Who buys it
- First: ward managers on surgical, renal and cardiac wards, where output is charted correctly only 21% of the time, and care-home managers (6.9% of UK care-home residents are catheterised). Next: community continence and district nursing services. Today they use a £3-15 wire stand, a £5 bed-rail urinal holder, a measuring jug and a paper chart.
- Why it pays
- A long-term catheter user costs the NHS about £1,191 a year, and 43% use out-of-hours services in a year; catching a stop 5-6 h before the next round turns some of these into planned visits (est.). Manual output charts are correct only 21% of the time, and BagPost's log is ±1.3-1.7% (est.).
- Target price
- $159 / £129 per stand, $79 / £65 per RailHook, $5/bed/month for the ward or care-home dashboard, $3/month for home users (target)
- First-minute wow
- A carer hangs the night bag at 22:00 and forgets to open the leg-bag valve; at 23:00 the shared phone says 'Room 12: no drainage since connected - is the leg-bag valve open?', and in the morning the manager sees every emptying already logged in mL.
What the research found
And how this design answers it
- Ward nurses chart output correctly only 21% of the time, and "void in toilet" with no volume is the commonest wrong entry (Lim et al., BJN 2021) → RailHook, a bed-rail urinal hook on the same load cell, logs every void in mL (±1.4-2.9%, CAD void report, est.)
- Blockage 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.)
- Carers leave the leg-bag valve shut after connecting the night bag → 'nothing drained in the first hour' alert
- Output is charted correctly only 21% of the time, and CQC has prosecuted a home over unmonitored output → every emptying is a weight step logged with its mL
- A bag on the floor or above the bladder → tap held 70 mm over a drip tray, and a fill limit for ultra-low beds (CAD height report)
- A tall stand tips at 4-10 N of push (CAD tip report), and tipping pulls on the catheter → a bed tether in the kit plus a 'stand knocked' alert
Use case
Night shift, 4 catheterised residents in a 60-bed home
Care workerNurseDistrict nurseResident
- 01Trigger: at 03:10 Room 7's drainage, normally about 50 mL/h, stops
- 02Detection: the Head's weight trend stays flat against the resident's 7-night baseline
- 03Alert: at 05:10 the shared phone says 'Room 7: no drainage for 2 h, check the catheter and follow the care plan'; the stand ring turns amber
- 04Action: the nurse finds the catheter bypassing and books the district nurse's 08:00 list instead of an out-of-hours call later
Outcome: The stop is handled hours earlier, and the whole night's output is already logged for the GP and the inspection (est.)
How it works
Architecture
- 01
Sense: a TAL220B 5 kg load cell with an HX711 in the Head; the bag hangs from the cell's free end on an M5 rod
- 02
Decide: the XIAO ESP32-C3 reads 2 s every minute, classifies steps (hung, emptied, knocked) and trends the drainage rate
- 03
Send: Wi-Fi MQTT/TLS to the IEMI cloud or a care-home Edge Hub; status every 10 min, events at once; no camera or names on the device
- 04
Tell: carer phone alerts, the stand's light ring, a 07:00 night summary and a dated output log for the manager and district nurse
Hardware
Real parts, buyable today
Bill of materials: about $84 per stand and $47 per RailHook at qty 1, about $48 and $26 at qty 100 (est.).
| Block | Part | Why this part |
|---|---|---|
| Bag weighing | TAL220B 5 kg straight-bar cell + HX711, printed 0.8 mm overload stop | 0.4 g ≈ 0.4 mL; a full 2 L bag is 44% of full scale |
| MCU | Seeed XIAO ESP32-C3 | Wi-Fi, deep sleep, built-in charger |
| Power | 18650 3,000 mAh + IP67 USB-C socket | About 58 days per charge (est.), no cable at the bedside |
| Status | Adafruit NeoPixel Ring 12 under a translucent lid + IP67 CHECK button | Fill gauge and alert colour, dimmed at night; CHECK logs the response |
| Stand | 16 x 1 mm aluminium tube + weighted printed Foot with a 1.18 kg steel plate and drip tray + bed tether | Tap 70 mm above the tray; the tether stops a bump tipping it onto the catheter |
| RailHook (urinal) | Same TAL220B + HX711 + XIAO ESP32-C3 + 18650 in a 46 x 100 x 44 mm rail case, J-cradle on an M5 rod | Bottle lifted, used and hung back = one void in mL; 10 s reads so a quick emptying is never missed |
Mechanical
Printable CAD
7 parts, generated from code and checked as closed solids. Pick a part to inspect it, or download the STL files to print.
See the CAD parts render
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Bought hardware fitted inside this part (checked in the CAD: nothing collides with the plastic)
- Head case: load-cell pillar and overload stop, rod hole, battery bay, USB-C and button holes, tube socket with thumb-screw bosshead-case.stl · ASA
- Head lid: light-ring cup under a 0.7 mm glow skinhead-lid.stl · PETG (translucent)
- Bag hanger: bar with 4 pegs for any 2 L night bag, M5 insert bossbag-hanger.stl · ASA
- Foot: weighted base with steel-plate pocket, drip tray under the tap, tube socketfoot.stl · PETG
- RailHook case: rides over a bed rail up to 30 mm, load-cell pillar and overload stop, battery, USB-C and button holesrail-case.stl · ASA
- RailHook lidrail-lid.stl · ASA
- Bottle cradle: J-hook with the cup under the rod, so the urinal pulls straight down the cellbottle-cradle.stl · PETG
Open risks we are working on
- Regulatory: US EXS urinometer is 510(k)-exempt only within § 876.9, and 'no drainage' alerts may need a 510(k) (gate R1: 513(g) or Pre-Sub); UK/EU class [UNVERIFIED], probably Im
- Prior art: Mikotek US12152923 (weight module vs expected output, carer alerts) and a BD smart-bag patent; freedom-to-operate is gate R2
- Low night output can cause false 'no drainage' alerts; test T1 over 20 resident-nights
- RailHook: urinal handle shapes and bed-rail profiles vary; tests T5-T6 on 3 brands and 5 ward beds
- A 470 mm stand tips at 4-10 N (CAD); the tether must be used, test T3
- Price anchor is a £3 stand and care homes are cost-squeezed; no manager or nurse interviews yet (gate G1)
- Coloplast, Convatec, Hollister or BD could add a sensor to a bag or stand
Design stage only: nothing on this page is for sale. Specifications and prices are targets.