Arrowcard

Inspiration

We’ve all felt it—that bittersweet feeling after an incredible event like IC Hack. The excitement of meeting inspiring people, the spark of new friendships, the energy of shared ideas. But when it’s over, there’s often a quiet sadness. Many consider the thought that we may never see some of these amazing people again. Challenging this notion is what has driven us to create ArrowCard, so that we can ensure those meaningful connections don’t just disappear. We wanted to replace that post-event sadness with something better: a fun and interesting way to stay connected.

What it does

During a networking event, participants will use lanyards similar to the IC Hack ones, each equipped with a microcontroller and a small display. By following on-screen instructions, they can easily pair their card with those belonging to others, storing all the connections made throughout the event. After the event participants can connect the card to a browser, upload their data along with their contact details and profile picture, and instantly access an interactive network. This network visualizes all the connections made by everyone during the event, showing how individual interactions grew into a larger web of connections.

This way, you can reconnect with people you might have otherwise lost touch with, as their contact details are easily accessible within the network. Another advantage is the ability to spark meaningful conversations—perhaps with a hiring manager—by seeing mutual connections formed during the event. What makes this truly special is that every connection requires a real, in-person interaction. Unlike platforms like Instagram or LinkedIn, where people often add contacts they’ve never met, ArrowCard ensures that every connection is built on genuine human interaction.

How it works

Each participant carries a lanyard with a microcontroller and a small display. This will display 5 arrows with varying rotations, forming a unique ID for the user. Other users will then use their own lanyards to enter this code, forming a link between these two users. A "check digit" arrow is also used to ensure the codes are correctly entered. At the end of the event, users will connnect their lanyards to their devices, and upload all their saved pairings to a central server, which will then form a graph that all users can view, showing all connections between all users.

The hardware is based on existing low-cost microcontroller lanyards. The firmware for the microcontroller is written in C++, and we used Rust on the server side, along with HTML, CSS and JavaScript for the frontend. WebSerial was used to fetch stored connections from the lanyards.

Challenges we ran into

We decided to use Rust for the server-side programming. This choice was done not because we believed it would be easier than python, but because it would be something useful to know. We, however, have underestimated just how much more difficult it is to programme a web server in Rust.

Acomplishments that we are proud of

We are very happy with the topic that we have chosen. It has taken us several hours to decide on a topic and we are very happy with the chosen one. That is especially because we feel that this idea might make sense for events which already spent a lot of money and spending something extra on cards with chips is not a big expense which can greatly increase the thrill and the memorability of the event.

What we learned

The part of the team working with Rust has noticeably improved with the language, however, one team member has vowed to never continue with Rust again. All of us had very little experience with frontend programming so we all improved quite a bit in that regard.

What’s next for ArrowCard

We think that the next logical step is to utilize an NFC chip. That way, it would be possible to simply put two cards next to one another and connect.

Built With

• c++
• embedded
• hardware
• javascript
• rust