Show HN: I'm a doctor and made a responsive breathing app for stress and anxiety

Hey HN! Some more info: I’m an NHS doctor and the founder of Pi-A (https://www.pi-a.io) which developed Lungy (https://www.lungy.app). Lungy is an app (iOS only for now) that responds to breathing in real-time and was designed to make breathing exercises more engaging and beneficial to do. It hopefully has many aspects of interest to the HN community – real-time fluid, cloth and soft body sims running on the phone’s GPU.

My background is as a junior surgical trainee and I started building Lungy in 2020 during the first COVID lockdown in London. During COVID, there were huge numbers of patients coming off ventilators and they are often given breathing exercises on a worksheet and disposable plastic devices called incentive spirometers to encourage deep breathing. This is intended to prevent chest infections and strengthen breathing muscles that have weakened. I noticed often the incentive spirometer would sit by the bedside, whilst the patient would be on their phone – this was the spark that lead to Lungy!

The visuals are mostly built using Metal, with one or two using SpriteKit. There are 20 to choose from, including boids, cloth sims, fluid sims, a hacky DLA implementation, rigid body + soft body sims. The audio uses AudioKit with a polyphonic synth and a sequencer plays generated notes from a chosen scale (you can mess around with the sequencer and synth in Settings/Create Music).

There are obviously lots of breathing and meditation apps out there, I wanted Lungy to be different - it's about tuning into your surroundings and noticing the world around you, so all the visuals are nature-inspired or have some reference to the physical world. I didn’t like other apps required large downloads and/or a wifi connection, so Lungy’s download size is very small (<50MB), with no geometry, video or audio files.

Lungy is initially a wellness app, but I’d like to develop a medical device version for patients with breathing problems such as asthma, chronic obstructive pulmonary disease (COPD) & long COVID. Thanks for reading - would love to hear feedback!