1. Concept 

Inspired by a speculative design by Modem, the breathing pod is a wireless handheld device that receives live breathing and heartbeat data over the network, expanding and vibrating accordingly.

I made a webpage to present the idea: https://breathingpod.framer.website/ 

2. Research question draft

Synchrony is the phenomenon by which people synchronize their physiological states (e.g. breathing and heartbeat patterns) when in co-presence.

The specific factors that influence the onset of synchrony are not yet fully explored, and after all, it can’t be telepathy. What matters most? Among all possible factors, like visual cues for facial expression or body posture, body temperature, auditory cues for verbal and paraverbal activity and breathing, smell and others, there are haptic cues about breathing and heartbeat.

When hugging or just touching a person, you can feel their chest expanding, and their heart beating.

In this sense, the research question would be: can people synchronize using a breathing pod (i.e. real time haptic information about another person’s breathing and heartbeat)?

3. Preliminary literature review and market analysis

3.1 Literature

3.1.1 Synchrony

1. Palumbo, R. V., Marraccini, M. E., Weyandt, L. L., Wilder-Smith, O., McGee, H. A., Liu, S., & Goodwin, M. S. (2017). Interpersonal Autonomic Physiology: A Systematic Review of the Literature. Personality and Social Psychology Review, 21(2), 99-141. https://doi.org/10.1177/1088868316628405 

Takeaway:

“[...] social processes operate at the physiological level.”

It’s an area worth exploring.

2. Bizzego, A., Azhari, A., Campostrini, N., Truzzi, A., Ng, L. Y., Gabrieli, G., Bornstein, M. H., Setoh, P., & Esposito, G. (2020). Strangers, Friends, and Lovers Show Different Physiological Synchrony in Different Emotional States. Behavioral Sciences, 10(1), 11. https://doi.org/10.3390/bs10010011 
   
   

3. Bizzego, A., Gabrieli, G., Azhari, A., Setoh, P., Esposito, G. (2021). Computational Methods for the Assessment of Empathic Synchrony. In: Esposito, A., Faundez-Zanuy, M., Morabito, F., Pasero, E. (eds) Progresses in Artificial Intelligence and Neural Systems. Smart Innovation, Systems and Technologies, vol 184. Springer, Singapore. https://doi.org/10.1007/978-981-15-5093-5_47 

Andrea Bizzego is my Neurotechnology professor, and the one I turned to to frame this project scientifically. I'm very happy that he will be my supervisor, as you can see from papers [2] and [3] that his work also focuses on synchrony measurement.

3.1.2 Biofeedback

4. Clara Moge, Katherine Wang, and Youngjun Cho. 2022. Shared User Interfaces of Physiological Data: Systematic Review of Social Biofeedback Systems and Contexts in HCI. In Proceedings of the 2022 CHI Conference on Human Factors in Computing Systems (CHI '22). Association for Computing Machinery, New York, NY, USA, Article 301, 1–16. https://doi.org/10.1145/3491102.3517495 

Takeaway: this is the paper that started my interest in this area a few months ago. Giving biofeedback in visual or numerical form is not enough, because we’re not used to perceiving and elaborating it that way. As Modem highlights in their article, it’s worth exploring new ways of sharing physiological data.

5. Kyung Yun Choi, Neska ElHaouij, Jinmo Lee, Rosalind W. Picard, and Hiroshi Ishii. 2022. Design and Evaluation of a Clippable and Personalizable Pneumatic-haptic Feedback Device for Breathing Guidance. Proc. ACM Interact. Mob. Wearable Ubiquitous Technol. 6, 1, Article 6 (March 2022), 36 pages. https://doi.org/10.1145/3517234 

Summary:

• Chest worn device that offers physical breathing guidance

• Pneumatic expansion feels natural

• Air pumps are loud

• No transmission of physiological data is involved

3.2 Market

1. Breathpod: https://www.breathpod.com/ 

• App for expert-led breathwork sessions and curated music

• Not on the market yet

• No embodied interaction

2. Moonbird: https://www.moonbird.life/

• Handheld device for haptic (mechanical) breathing guidance and heartbeat readings

• Offers breathing guidance based on recordings or user defined pace. Reads heartbeat to give biofeedback

• No sharing of physiological signals

• Design process: A handheld tool for personalised breathing exercises - Achilles Design 

• Expansion visible at 1’09’’ moonbird (Honest Review) | Hand-Held Breathing Device 

4. Prototype

As detailed in the website, the long term goal is to have a system comprised of three parts:

• Sender. A chest belt sending breathing and heartbeat data

• Receiver. A wireless expanding and vibrating pod that receives data collected by the belt

• Mediator. App or web interface mediating data and biofeedback across devices

Fig. 1 Long term breathing pod setup: wireless belt, wireless pod, mobile interface

4.1 Current state: proof of concept

For the scope of the current research, the interface mediation is not necessary - belt and pod can communicate directly.

I’ve used two ESP32 boards to build sender and receiver, which communicate wirelessly through ESP-NOW, a low latency communication protocol built specifically for these boards by their manufacturer Espressif, with a range of about 220 meters. While this range is not compatible with the long term remote networked interaction envisioned, it is enough to conduct experiments with participants in different rooms.

4.1.1 Setup

The current setup consists of two ESP32 boards mounted on breadboards for quick prototyping. The videos below show the prototype in action, communicating wirelessly - the white USB-C cables are only for alimentation.

Watch the videos with sound to listen to breathing, get a sense of latency, and hear the vibration in Video 2.

Video 1 Expansion mechanism in action: https://photos.app.goo.gl/wma72ARCgyXfHWR69

Video 2 Heartbeat vibration: https://photos.app.goo.gl/Qu1HjUi4Am2RGUt38 

Fig. 2 Full setup, using the Pulse Sensor Amped from Adafruit, an optical heart rate sensor (PPG)

Fig 3 Alternative sender setup, using the AD8232 ECG Measurement Heart Monitor Sensor Module

4.1.2 Sender

To collect breathing data, the sender makes use of a non-elastic adjustable belt, joint closed by an elastic stretch sensor, which is a conductive rubber cord (Fig 4). Here is the ScienceBuddies project I followed. The belt can be worn over clothes reliably, as a calibration of chest movements is performed in the first 10 seconds of use.

Fig 4 Chest belt

To collect heartbeat information, I’ve tested two sensors:

1. Pulse Sensor Amped from Adafruit, an optical heart rate sensor (PPG)

• Pros: comfortable use, as it can be worn on a finger or on a ear lobe with the provided clip

• Cons: unreliable readings (I need to do some troubleshooting)

2. AD8232 ECG Measurement Heart Monitor Sensor Module

• Pros: reliable readings

• Cons: cumbersome to wear, as it needs three electrodes on the torso

The two sensors are interchangeable in the current setup, as they both work on 3.3V and their signal is compatible with the PulseSensorPlayground library.

4.1.3 Receiver

In collaboration with Trento’s FabLab, we found that the most simple, reliable and convenient solution for the expanding mechanism is a servo actuator pushing a rod. The idea is to have two half shells, sliding into each other. The servo is mounted on one half shell, while the rod is connected to the other.

Video 3 Servo pushing a shell through a rod: https://photos.app.goo.gl/b92ZYmLifUuKidRH6 

While the current proof of concept is just a paper box (Fig 5), the next step is to model and 3D print a round shaped version. A coin vibration motor vibrates for 200ms everytime a heartbeat is detected.

Fig 5 Breathing Pod proof of concept made of paper.

5. Next steps

Prototype

• Make a 3D printed, round shaped version of the pod

• Make the pod wireless, or at least possible for participants to comfortably hold it in their hands

• Troubleshoot Pulse Sensor Amped signal

• Tidy up the chest belt’s cables for participants’ use

Research

• Research design

• Pilot & Experiments