Hand tools and fabrication machines
DISCLAIMER: Due to the Lockdown concerning COVID-19 there has been a few resource constraints and the final Prototype is a slight deviation from the actual concept.
While going through the various symptoms relating to Peri/-/Post-menopause. Initially, we were focused on the psychological aspects a woman has to deal with and the problem of hot flashes(HF) intrigued us. We quickly zeroed in the fact that the solution to this problem is within our grasps and started brainstorming prototyping ideas.
We created Slip Stream a wearable garment with integrated fluid channels to circulate cool water throughout. The warmed-up water is circulated back to the thermoelectric cooling module, after which it is pumped back to the channel network.
Due to the resource constraints, we decided to develop only an arm piece of our concept garment. Here the originally intended plastic micro-tubes were replaced with channels formed by welding together poly sheets.
The suitable flexible tubes of millimeter range (2-3mm) weren't available; we decided to weld plastic sheets together and make them into channels. This was a difficult task and took some experimenting to arrive at the optimal method to do it.
Running a hot Soldering iron on the plastic sheets sealed them perfectly. The tubes were created by inserting a metal wire/rod of the required diameter and sealing both sides and pulling out the rod after that.
Ideally, there can be multiple parallel flow channels distributed in different directions. This will also reduce the pump load and improve efficiency by decreasing flow speed allowing ample time for heat transfer.
The Pump draws in water from the channel network and pumps it back via the thermoelectric module. Here two 30mmx30mm Thermoelectric tiles were used which cooled the water captured in a bottle cap.
All water joints in the bottle cap trap(see image) were sealed with epoxy putty, which also helps in insulating the cold side of the thermoelectric tile which remain uncovered by the bottle cap trap.
The Tyranny of the Thermoelectric module: These modules are notoriously inefficient but in this case, there is a silver lining to it. Hot Flashes last for 5-10 mins (the flow time can be customized by the user or automated) and then followed by lowering or core body temp which give 'chills'. To our advantage then the Flash has passed the electric coolers turn off this caused the heat from the hot side to flow back to the cool side, and due to the inefficiency, there is more heat energy than you start with. This extra heat can be taken up by the flowing fluid (water)to warm up the stream and heat up the body and even further, the polarity of the thermoelectric converters can be reversed (using an H-Bridge like L298N module etc.) This will cause a warm stream to flow through the body and hence maintain overall thermal comfort.
Thus my reversing the polarity of the thermoelectric module 'Slip Stream' acts as a body heating device as well, increasing its use cases to outdoors and workplaces as well, when powered by a portable Lithium-Polymer battery, etc.
NOTE: This this prototype we have not included the polarity reversal aspect.
While testing the cooling module we burnt our last Transistor which were acting as a switch for the pump and the Thermoelectric modules. An impromptu switch was made using a servo motor arm to connect and disconnect the said circuit using the Arduino nano. So instead od signaling the transistor the Arduino controlled the servo motor. Here is the video..
The heat sinks and the cooling fan are an essential part and ensure higher cooling efficiency. The poly sheet channels are meant to be integrated within cloth material. Blue color was added to the flowing water. While our current prototype is powered from a power supply unit it can be integrated with a battery pack or a thermos full of cool water( so it doesn't require electric power to cool)! Multiple variations are possible!
We hope you liked our project!