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Background

Astronauts, after long-term exposure to low gravity environments such as during extended space flight missions, experience a number of health complications as a result. On Earth, the human body has adapted to the planet’s gravity and is able to pump blood evenly throughout the circulatory system. Therefore, when in space, blood tends to have a net upward movement in the body since the downward force of gravity is no longer present. The higher volume of blood in the upper body and most importantly in the brain eventually leads to a decline in cognitive performance. In addition, muscle atrophy in the legs of astronauts has also been observed due to the lack of physical exertion typically needed on Earth to hold oneself upright. Therefore, it is necessary to develop a method of simulating the effects of gravity for astronauts participating in long term space flight missions. 

The Proposed Solution

The Lower Body Negative Pressure device aims to recreate the effects of gravity by applying a pressure lower than the ambient pressure (referred to as negative pressure) around the lower body. 

Problem Statement

Although the device is able to generate a negative pressure in its chamber, the negative pressure generated is not high enough to create a physiological difference and the device is unable to sustain its negative pressure for a significant amount of time. In particular, the maximum negative pressure achievable was limited to 10 mmHg due to deformation of the chamber. Additionally, the cause of the pressure leakage was identified to be  an improper seal between the user’s lower back and the waistband of the device. As a result, the chamber lost all effective negative pressure (> 6 mmHg) in approximately 40 seconds. 

Primary Objectives

• Increase the maximum negative pressure achievable to 20-25 mmHg. 

• Improve the waistband seal of the device such that the chamber’s negative pressure remains above 10 mmHg for at least 1 minute. 

• Minimize device weight to below 50 kg.

Final Design Overview

The device was modified to meet the specified objectives by creating an internal structural support system consisting of carbon fiber rings to prevent chamber deformation and by adding a customized belt strap to support and improve the waistband seal.