We introduce–aSpire–a clippable, mobile pneumatic-haptic device designed to help users regulate their breathing rate via subtle tactile feedback. aSpire can be easily clipped to a strap/belt and used to personalize tactile stimulation patterns, intensity, and frequency via its array of air pouch actuators that inflate/deflate individually. To evaluate the effectiveness of aSpire’s different tactile stimulation patterns in guiding the breathing rate of people on the move, out-of-lab environment, we conducted a user study with car passengers in a real-world commuting setting. The results show that engaging with the aSpire does not evoke extra mental stress, and helps the participants reduce their average breathing rate while keeping their perceived pleasantness and energy level high.
We introduce–aSpire–a clippable, mobile pneumatic-haptic device designed to help users regulate their breathing rate via subtle tactile feedback. aSpire can be easily clipped to a strap/belt and used to personalize tactile stimulation patterns, intensity, and frequency via its array of air pouch actuators that inflate/deflate individually. To evaluate the effectiveness of aSpire’s different tactile stimulation patterns in guiding the breathing rate of people on the move, out-of-lab environment, we conducted a user study with car passengers in a real-world commuting setting. The results show that engaging with the aSpire does not evoke extra mental stress, and helps the participants reduce their average breathing rate while keeping their perceived pleasantness and energy level high.
(a) aSpire, a clippable pneumatic-tactile feedback device with 3 soft actuators. (b) Control UI that allows users to select/create different tactile patterns. (c) User test of aSpire on passengers in on-road commuting environment. aSpire clipped on; (d) a seat-belt for breathing guidance and providing comfort for vehicle passengers, (e) a back pack strap during walking.
1. We implemented a mobile GUI (Graphic User Interface) for allowing users to personalize their own tactile patterns delivered by the aSpire and control it.
Mobile UI for aSpire control
2. Evaluation on its tactile intensity control system has been done
3. User study protocol for evaluating the aSpire system in various daily activities (walking, driving, desk work) other than commuting in cabin as a passenger has been submitted to the institutional review board and planning to run it at HMC R&D center.
4. Thanks to the member collaboration with HMC (NVH Research Lab, PI: Jinmo Lee), we deployed the aSpire on a Hyundai toy car for mitigating stress and anxiety of pediatric patients waiting for getting a surgery in SJD Barcelona Children's Hospital (Project Video in YouTube)
Courtesy of Hyundai Motor Company
aSpire on a toy car developed by HMC for pediatric patients
Courtesy of Hyundai Motor Company
Welcome to the aSpire project
Hi! I'm Kyung Yun Choi (please just call me Yun), first year PhD student at the Tangible Media group and PI of the aSpire project. My background is Mechanical Engineering (BS) and Aerospace Engineering (MS), and my research efforts revolve around creating a new tangible interface that extends the space of user experience by enabling the transmission of emotional and tactile information.
I am excited to introduce our collaboration project with ML member company Hyundai Motor Company (PI: Jinmo Lee), the Affective Computing group (Dr. Neska El Haouji, Prof. Rosalind W. Picard) and Jessie Wang (undergraduate student in M.E), which was initiated to provide physiological and physical comforts to passengers in a future self-driving car. However, we are not only constrained in the on-road car application, but also have been exploring the potential deployment of this research in daily activities, as shown in the figure above as a few examples.
Let me explain more details below; 1) how we started to come up with this idea, 2) how we implemented this compact and mobile tactile feedback system, 3) how we evaluated this system, and conducted a user study and its result, and 4) lastly, potential applications that could be benefit from using aSpire in daily routines.
Regular practice of slow and deep breathing has gained lots of attention thanks to its health benefits [33] such as enhancing ventilation efficiency of respiratory system, heart rate variability, and lowering of blood pressure [22, 63, 27, 49]. Breathing exercise also has physiological benefits such as reducing mental stress, anxiety, and depression, and promoting a generalized state of relaxation [27, 7]. Since breathing provides an efficient way to voluntarily and indirectly control our physiological state, including heart rate and heart rate variability [27, 65], it has been known as the oldest stress-reduction technique [15]. Various types of techniques that involve slow, deep breathing such as yoga, Tai Chi, and some forms of meditation, have been practiced throughout history to increase well-being [61, 41].
A growing number of studies in Human-computer Interaction (HCI) have developed and explored new interfaces to assist people to regain and sustain attention to their inner body through breathing [46].
However, despite making many advances, most of the devices lack mobility and a convenience that enables them to be deployed and tested in natural daily-life environments. Also, their studies have neither examined pneumatic-tactile feedback for guiding breathing rate (BR) control, nor have they evaluated effectiveness to allow people to have various options for getting tactile biofeedback. Lastly, it is difficult to find a tactile biofeedback system that provides adaptive intensity to adjust to different body shapes and user’s preferences, due to the lack of feedback control ability.
aSpire in the motion of rendering the sequential tactile pattern
To promote breathing exercises that are convenient to test in daily life, we introduce aSpire, a mobile tactile feedback device that enables users to control their BR while maintaining a high energetic and pleasant level, without evoking stress.
Two different tactile patterns from aSpire
Our goal is to develop a non-intrusive tactile feedback device that guides users to regulate their BR during daily activities without inducing extra mental stress. We focused on the tactile modality as opposed to other sensory modalities for influencing BR. To achieve our goal, we have set the following design requirements:
(a) Overview of aSpire (b) Electronic system diagram of pneumatic control module (c) Inner view of the aSpire when the actuator clips open. (d) Hardware configuration of (c) pneumatic control system using 3D printed air flow multi-channel structure to increase space efficiency
aSpire consists of three soft air pouch actuator modules and a pneumatic control system module. Each actuator is paired with a 3-way solenoid valve. The DC motor air pump is connected to two solenoid valves that control the open/close of the outlet and inlet of the motor. Based on these 5 solenoid valves’ ON/OFF state combination as shown in the state table (figure below (b)) and its ON/OFF duration, the system can individually control the deformation speed of the actuator using a single motor.
The maximum speed of the DC motor air pump is 18.5 ml/sec for inflation, and 21.4 ml/sec for deflation. This enables the system to deliver up to 15 bpm with various tactile patterns. When the motor was running at the maximum speed, the noise level was measured as 62 dB from the 1 cm distance, and 38 dB from the 30 cm distance. This maximum noise level is relatively low given the noise from a conversation in a restaurant or office may be around 60 dB. When the motor was running at the average speed, the noise level was measured as 43 dB from the 1 cm distance while it was 28 dB from 30 cm distance (ambient noise was 24 dB). The maximum normal contact force that the actuator can handle was measured as 17.7N. The dimension of the single soft air pouch actuator is 58W x 67L x 15H mm. The dimension of the pneumatic system module is 99W x 67L x 38H mm. The total weight of the device is 252 g. The silicone we used for fabricating the sensor and actuator has a 900% elongation at break, which led us to achieve a maximum z-direction (height) strain of 32 mm, and the maximum volumetric displacement of 40 ml for inflation and 17.5 ml for vacuuming from the default state. At the maximum-inflated state, the pressure inside the actuator goes up to 1054.57 hPa on average (10.6 Mohm) where the average atmospheric pressure was 1010.89 hPa measured from the barometric sensor. When the motor fully vacuums the actuator, the pressure of the actuator drops down to 872.73 hPa (490.8 Kohm).
To develop the device compact and mobile, we created a stretchable pressure sensor that can be integrated as a part of the actuator material, instead of introducing an extra barometric pressure sensor tethered to another air channel tube branching from it connecting between actuator and pump, which is commonly used in a pneumatic system. We embedded the sensor system on the air pouch actuator membrane that responds to the volumetric deformation of the actuator by varying its resistance value.
We ran the inflation/deflation cycle of the soft air pouch actuator with 12 bpm speed for 160 min to have it run for 1920 cycles for a durability test of the stretchable sensor and for inspecting the peak-to-peak value variance. After running the 1920 cycles, the barometric pressure sensor’s the peak-to-peak value root-mean-square error (RMSE) was 8.86% while the stretchable pressure sensor had the RMSE of 7.69%. We used the data acquired from the cycle test for a sensor calibration.
Animations shown below present the sensor response to different force inputs.
Sensor response to the synchronized tactile pattern with different input pressure
Sensor response to the sequential tactile pattern in different rhythm
User study on passenger in a on-road car
Most people in the U.S spend 43 - 53.2 minutes on average per day on the road to commute in a car or train [29] and this average commute time has kept growing since 2009 [8]. Reflecting on this trend, we chose to evaluate the potential real-world daily situation of using aSpire while riding in a car.
We drove a four-door midsize sedan on a designated round-trip driving route alongside a river in Cambridge. The driving route was a two-lane road with a speed limit of 35 miles per hour and 9 mile distance in one way, which took 30 minutes of driving. We divided the route into four segments to test four different conditions of the aSpire operations for 5 min each. We conducted the study between 10 AM to 4 PM on weekdays and weekends to avoid the rush hour traffic for minimizing the uncontrolled variables.
A total of 18 participants ranging from 20 to 38 years old (M = 28:56 years, SD = 5:06 years) took part in the study, including 8 females and 10 males. The first three participants were pilot testers.
User study result (a) effect on breathing rate (b) effect on passengers' EDA level
Eight participants commented on the feelings and emotions induced by the use of the device, four of them reported the feeling of a pet or person presence, while four reported more focus, calmness and more comfort when using the device in the seat belt.
One participant highlighted the usefulness of such device attached to the seat belt to appreciate the wear of the seat belt while it is usually uncomfortable to put.
Three participants comments can be classified related to the use of the device, two recommended using it while driving and another as a device to help kids to sleep.
One participant reported that it would be more relaxing to have warmth from the device while getting the tactile stimulation which could make this feeling more similar to hugging someone.
Only one reported a remark related to the design, wishing to have the device along the whole seat belt, proposing then to enlarge the contact surface with the body.
(a) Preferred stimulation (b) Potential activities that aSpire device can help with.
(a) User study example of a male passenger (184 cm height) (b) Operation in synchronized mode
A 73% of participants reported that the aSpire would be effective for stress relief, we think that applying aSpire for a car or bus seat-belt, or perhaps an airplane seat-belt (this would need more testing because of the lap position), could enhance comfort and relaxation during travel and commutes. Some visions of the future include autonomous cars with the potential of the car cabin becoming a place for greater relaxation and well-being. Since most participants perceived the sequential tactile pattern as massaging, and the synchronized tactile pattern as soothing, aSpire may help enable such a future vision.
Mitigating stress of driver and alerting when the driver feels drowsy
Given the device’s demonstrated potential to support reaching a lower goal breathing rate (GBR), we think that setting a higher GBR might also be effective. A few participants reported that condition (sequential tactile stimulation pattern) felt like awakening them, and the work by Russo et al. presented benefits of increasing the BR as alerting and increasing focus. Thus, future work should evaluate the potential of aSpire’s programmability, using different settings, to help users achieve different types of desired benefits.
As we currently developed two aSpire devices, we hope to explore the potential usage which is for enhancing communication over distance/in a same space via tactile feedback. aSpire could be used for enhancing the physiological and emotional connectedness of a couple who are communicating through video conference while walking on a road/staying in a room by delivering each other's BR phase and rate. Not only for this physiological connectedness, but the aSpire could be used as a playful and interactive tactile communication tool- as TMG showed several examples such as inTouch, and PegBlocks- via distributed aSpire's symmetric/asymmetric connected inflation and deflation motions in response to users' touch and pushing force. Detailed concept of physiological connected ness via biofeedback interface can be found in my MAS thesis (BioResonant Interfaces: Tangible, Subliminal Biofeedback to Regulate Physiological States, MIT) page 62 - 65.
✔ Working prototype is developed as described and demonstrated in the video and the photos above
✔ Technical evaluation of the hardware and system is done
✔ User study with passengers in a real-world commuting car setting was conducted
✔ Data analysis of the passengers' physiological state (heart rate, skin conductance level) is done
✔ Academic paper has been submitted to ACM CHI 2021 conference (the acceptance notification will be out Nov.)
✔ Tech-Disclosure and provisional patent have been filed
✔ We are planning to run another set of user study in Korea (HMC R&D Center) for evaluating the device in multiple use-case scenarios (Walking, driving, office works)
Currently, the details of the introduced technology is under review process of the international ACM UIST (User Interface Software and Technology Symposium)2020 conference; once the paper get accepted, we can share more details and the published paper after October 20th, 2020.
We are envisioning to deploy the aSpire in a larger scale form-factor in a car environment not only as a clippable to a seat-belt but also as be a part of the car interiors. Also, as described in the application section, we hope to evaluate its effectiveness in various daily activities. Especially, supporting the yoga trainee and weight-trainer with breathing rate and phase feedback and investigating if the aSpire could improve their athletic performance would be really interesting.
If you want to hear more about our vision and discuss about potential ideas, please contact us! :)
Please send an email to Kyung Yun Choi (yun_choi@media.mit.edu).
Hyundai Motor Company recently unveiled a miniature electronic vehicle that uses Emotion Adaptive Vehicle Control (EAVC) technology.
Massachusetts Institute of Technology School of Architecture + Planning
Accessibility Donate to the Lab