Keep attackers at bay with a stink bomb bracelet

Figures from Statistics Netherlands reveal that about two in three young women (up to the age of 25) say that they have been harassed on the street at some point in 2021. The abuse ranges from being yelled at, whistled at and hissed at, as well as being stalked. Most women ignore this kind of thing, but are left with a feeling of unease. “It makes them feel less confident to go out on the street,” says Roel van der Kamp in this intstalment of Start-up of the day. Van der Kamp is the founder of Invi Bracelet, a bracelet containing a hyper-concentrated stink bomb to keep assailants at bay

Why was it so important to you to do something about this?

“”In 2014, I read some research on sexual violence. I then started talking to my sister and friends. I thought the numbers were really devastating and wanted to know if they had to deal with this too. This really shocked me, you think it doesn’t happen in your own surroundings, but it was also going on in Rotterdam where I was studying at the time. It has such an impact on people, not just women by the way. But it is so unjust that I really wanted to do something against it.”

How did you come up with the idea of a bracelet?

“I was especially amazed at the means people use to defend themselves. Like keys between their fingers to keep any attackers at a safe distance. Or they walk around with potato peelers in their bags. Even cans of pepper spray. These are fairly aggressive measures that could provoke more violence. You have to decide in a split second. Just try to grab the pepper spray in time and aim it precisely at the attacker’s face. What’s more, pepper spray is illegal in the Netherlands.”

Should I think of the smell as reminiscent of ‘old-fashioned stink bombs’ in a dissolvable material?

“Yes, the smell may be comparable to that, but it is much, much stronger. Hydrogen sulfide is contained in those ‘bombs’, which gives off the familiar stench of rotten eggs. But this substance is harmful, so we weren’t able to use it. This is where it gets tricky. Why do we think something stinks? That’s because most things that stink are bad for our health. It’s not for nothing that you get a feeling of revulsion when you smell spoiled food. Your brain is basically warning you so that you don’t come into contact with pathogens. So, we had to look for something that does evoke those instant feelings of disgust and repulsion without actually being harmful to your health.”

“After a long search, I got in touch with a research group made up of international scientists who also do research for the Dutch Ministry of Defence. They did not want to share their formula until the University of Wageningen and Groningen and TNO also became involved.”

Can you tell us how it works?

“You can break the vial in the bracelet by giving it a simple pull, but you still have to press the safety button first. With this two-stage safety mechanism, you can never break the vial by accident. But in stressful situations, when your fine motor skills are diminished, it is still easy to do. The odor is released after only a few seconds. The attacker is shocked and disgusted by the stink. This increases the likelihood of being able to get away or get help. Also, the stench alerts bystanders. The fire service has turned up several times because they received reports of a gassy smell. That freaks you out at first, but actually we think this is justified if someone is really in need.”

Does the bracelet work?

“Research we have done with the University of Groningen and Wageningen has shown that the stench triggers so much revulsion that it can ruin the sexual arousal of attackers. It should be noted that sexual assaults are not driven solely by lust. But attackers are deterred by the rancid smell, it deflects their aggression, and it gives the wearers just a little more time to call for help or to run away. Without directly harming the attacker or allowing the product to be used against you, as is the case with pepper spray.”

“The bracelet has already prevented several attempted rapes. These are still extremely distressing experiences, but fortunately we have been able to prevent them from becoming worse. Moreover, we hear from a lot of people that they feel safer wearing the Invi Bracelet. It gives them that extra bit of confidence and that is what you radiate. It is also something psychological.”

What is the biggest challenge you face?

“The fact that you can use odor to protect yourself takes a lot for people to be able to imagine. Apart from that, sexual violence is a sensitive subject. We try to open up this discussion in the right way. It’s good that more and more attention has been paid to it recently, but I hope that this also translates into a change in behavior. I’m hoping that a kind of counter-movement will develop; men in particular can contribute to this by calling each other to account for their behavior. I want a world in which those who intimidate, assault or rape feel unsafe themselves.”