HERO Inner-Mask is an accessory that reduces the suffocation caused by the usage of non-woven (surgical) masks by regulating the airflow inside them.

HERO Inner-Mask

Appearance of HERO Inner-Mask
  • Comfort breathing and conversation
  • Prevents fogging of glasses
  • Prevents makeup smudging
  • Pocket size foldable frame

To appropriately and effectively wear a non-woven mask

Studies and observations suggest that wearing a non-woven (surgical) mask, rather than a cloth mask or urethane mask, is extremely effective in preventing COVID-19 infections. However, owing to the high filtering performance of the non-woven mask, it is easy to feel stuffy when using this mask. The currently available commercialized assistive products for non-woven masks solve this problem by lifting the mask from the mouth or skin; however, the exhaled breath, which is inhaled again, still fills the environment between the mask and the month of the user. As a result, some people move the mask down to expose their noses, undermining the prevention effectiveness.
To address this problem, HERO Lab has started to develop HERO Inner-Mask that does not suffocate the user, even when properly wearing the non-woven mask.

non-woven (surgical) mask

Rectifying structure that
employs the human breathing mechanism.

Figure 1 indicates that inhalation and exhalation are naturally separated mechanisms, as inhalation involves the slow suction of stationary air near the nostrils, and exhalation corresponds to the air being blown downward as a jet from the nostrils. However, when you wearing a mask, the room inside the mask is filled with exhaled air, and the foul air is inhaled again, causing discomfort.
When using the HERO Inner-Mask, the space inside the mask is divided into upper and lower parts by a "partition plate", separating the inhalation and exhalation mechanisms, therefore assisting the breathing of humans. Fresh air enters from the space above the mask during inhalation and the air jetted from the nostrils during exhalation exists through the lower filter, which is composed of non-woven fabric. In addition, the probability of the occurrence of foggy glasses decreases, as the exhaled air does not flow back upward owing to the partition plate.

reciprocating flow of breath

Figure 1: Visualization of the respiratory reciprocating flow using a supercomputer

Source: 2009 RICC Usage Report by Toshihiro Sera ‘Calculation of Airflow in the Human Upper Respiratory Tract’

Rectification Mechanism

inhalation exhalation

The partition plate of the HERO Inner-Mask divides the space between the mask and the mouth of the user into upper and lower parts, the air flow easily from the top part to the bottom part (rectification effect). In this structure, the exhaled air does not remain near the nostrils, and fresh air always enters the mask from the outside environment through the upper filter.

Verification of the rectification effect using a thermography camera

The rectification effect was verified using a thermography camera, which shows the temperature difference of the face of the user. The mask without the HERO inner mask shows red due to the heat generated by the exhaled breath, indicating that the temperature had risen. As the temperature change spreads throughout the mask, the exhaled breath fills the entire space between the mask and the mouth of the user.
In contrast, when using the HERO inner mask (right side of the figure), it can be seen that the exhaled air is smoothly exhausted to the lower part of the mask, suppressing the overall temperature rise. Furthermore, the blue spot on the mask indicates that the temperature is relatively low, as the backflow of exhaled air is suppressed to the upper space.

  • Experimental conditions

  • Room temperature: 0℃
  • Non-woven mask: Diamond-shaped non-woven mask(KUCHIRAKU MASK/iSDG ishokudougen.com)
  • Thermography camera: FSV-1200-L16 (Apiste) [Specifications] Measurement accuracy: ±2 °C / Effective pixels: 320 × 240 / Measurement wavelength: 8–14 ㎛
    [Measurement temperature setting range] 8–25 °C
Non-woven mask used in this experiment

Non-woven mask used in this experiment

A pioneer in the robotics,
Professor Emeritus Hirose of Tokyo Institute
of Technology designed the HERO Inner-Mask.

Shigeo Hirose

[HERO Lab.]
Hyper-Environmental Robots Laboratory
Director Shigeo Hirose

Hirose is a Professor Emeritus at the Tokyo Institute of Technology (Tokyo Tech). He has worked as a distinguished professor in the Department of Mechanical and Space Systems, and is a director of the Super-Mechano-System Innovation and Development Center in Tokyo Tech. He has created and developed various robots and machine elements such as snake robots, walking robots, and robots of variable shape. These robots were applied in disaster rescue works, landmine detection and removal works. He has applied for more than 1000 academic treatises, the largest number of patents among professors at Tokyo Tech, during his tenure. He has also been committed to creativity development education beyond the boundaries of the university as well as on the campus. In June 2020, Hakusan Corporation established HERO Lab, and Hirose became the director of the laboratory.

Awards and Honors
IEEE Pioneer in Robotics and Automation Award (1999), Department of Science Award (2001), Medal with Purple Ribbon (2006), Joseph F. Engelberger Robotics Award (2009), Japan Society of Mechanical Engineers Technical Achievement Award (2013), IEEE Inaba Technical Award for Received Innovation Leading to Production (2017), The Order of the Sacred Treasure - Gold Rays with Neck Ribbon (2021), etc.

A story of product development

In the summer of 2020, when I was riding a bicycle while wearing a mask, I wondered if I could reduce high temperature and closeness by the use of surgical masks; therefore, I started developing the HERO inner mask. Several products available in the market that allow the mask to float from the mouth; however, wearing it for a long duration leads to suffocation, and hinders its filtering effect if the mask is not properly worn. I believed that we require a mask accessory that allows the user to breathe more comfortably, even when the mask is worn properly.

To eliminate this suffocation, I believed that it is important to induce an airflow inside the mask from the top part to the bottom part and regulate the flow in one direction through an electric fan and a small turbine that rotates due to the exhalation from the nostrils. I have developed several prototypes to achieve practicality and solve the suffocation issue using the simplest possible mechanism, similar to a physical check valve. As a result of repeating experiments, in which 100 or more prototype models were attached and exercised, I concluded that a simple hole on the “partition plate” can be sufficient, instead of a check valve.

While the exhaled air from the nostrils has kinetic energy; therefore it can easily pass through the holes in the partition plate, moving downward. This is because the inhalation is caused by the suction of stationary air around the nostrils, which does not result in backflow of the exhaled air from the lower side. The simple hole and plate alonesufficiently block the backflow of the exhaled air, inducing the same effect as that of a check valve. A unique structure that rectifies the inflow and outflow of air from the nozzle (nostrils) makes this possible.

prototype of HERO Inner-Mask Prototypes of HERO Inner-Mask

Hirose’s column

Why do human inhale and exhaust air through their noses?
Why has the nasal cavity evolved so thin that it can get clogged by empyema?

Find out more

User questionnaire survey

* Results of the questionnaire conducted 261 people, which were surveyed by Hakusan
from 20th June to 20th August 2021

  • Feel easy to breath100%
  • Prevent glasses from
    getting foggy
  • Reduce discomfort of
    wearing a surgical mask

HERO Inner-Mask is
available here. an external link(No overseas shipping is available, currently.) Amazon