How I solved another invisible barrier: the sensor that tells me when to empty my urine bag

One more step toward independence and peace of mind.

Let’s be honest—wetting yourself is one of the most frustrating things that can happen when you have quadriplegia.
And when it happens to me, I totally lose it.

Imagine sitting in an important meeting—and having no way of knowing if you’re about to pee yourself. There’s no worse feeling.
That used to be my daily reality—until I built a sensor that discreetly tells me when it’s time to drain the bag.

Real-life scenarios where this sensor helps

• In winter, when I’m wearing thicker pants or have a blanket over my legs—I can’t see the urine bag.
• Indoors, surrounded by unfamiliar people.
• At multi-day seminars or conferences (some lasted from 10am to 5pm, for three days straight).

I was alone in a room full of strangers, all day long.
And in those situations, it’s really awkward to ask someone you don’t know to lift your pant leg just so you can check the bag.

Sure, someone will probably help—but when it comes to personal things like this, I don’t want to seem pathetic.
To most people, just seeing a wheelchair is enough to make them think your life is pitiful. Many associate wheelchairs with helplessness, poverty, or tragedy—because deep down, they fear it could happen to them one day.
We’re easy to ignore. We “ruin the view.”
Kids stare at us in parks like we’re part of a freak show.

But…

My wheelchair is not a symbol of limitation—it’s my vehicle of freedom.
What I used to see as weakness, I now see as strength.
My chair isn’t a barrier—it’s the reason I can be present, independent, and free.

As someone once beautifully said:

“A wheelchair is a vehicle to liberation and freedom; a chariot for independence.”

And they were absolutely right.

The idea behind the sensor

The whole point of this sensor was to solve a very specific problem—those moments when I’m in public and can’t easily check the urine bag.
It’s one more micro-step toward independence.

That’s why I constantly adapt and combine technology to suit my own needs.

How it works

My bag is attached below the knee.
The sensor is stuck to the outside of the bag, about 2/3 of the way up. If you look closely at the photo, you’ll see a green LED.

Once mounted on the leg, the small wire with the LED drops slightly below the pant leg—just behind the heel.
So when I glance down, I catch the light in the corner of my eye.
That light means: It’s time to empty the bag.

Discreet. Effective. Problem solved.

This sensor might not be essential for everyone—but if you spend a lot of time in public or social spaces, you’ll understand its value.

I don’t wear it all the time, but I always have it ready when I need it.

Installation & details

• The sensor is placed at 2/3 of the bag’s capacity
• It attaches with adhesive Velcro tape (easy to remove and reattach)
• No contact with urine
• LED indicator discreetly signals when it’s time to empty
• The control box under my seat has two 3.5mm female audio jacks—one 5V output for the sensor and one 24V for the electric drainage valve

This is a contactless ultrasonic sensor used for monitoring liquid levels.
It’s commonly used in water tanks, fuel barrels, and aquariums to prevent overflow.

Here’s a video about it:

It’s small, lightweight, attaches with Velcro, and hides easily under the pant leg.
When using a new urine bag, just add a new Velcro strip and reattach the sensor.

Part of a larger system

This sensor is the next layer of improvement, when paired with my electric drainage valve.

I built this setup years ago, and since then, the number of available sensors has grown—different shapes, sizes, and colors can be found on sites like AliExpress.

Final note

At the time of writing, I’ve changed power wheelchairs, so the full installation has been removed and is waiting to be set up on the new chair. Photos were taken just for reference. Once I reinstall the full system, I plan to film a video demo and write a new article showing the real-time functioning of both the drainage valve and the urine level sensor.

As far as I know, this complete system is one-of-a-kind. I haven’t seen anything like it online—so I proudly stand behind it.

Of course, it can always be improved and customized for different needs.
My version is pretty simple—easy to build, easy to use.

But it gave me something priceless:

Peace of mind
If you want to stop worrying about wetting yourself in public—try this.
If you already have a setup, share it in the comments—together, we can make life easier for others.

Because freedom shouldn’t depend on guessing—or hoping someone else notices.