Enhancer mask

Description

The mask constantly records the biomedical data of the wearer and, if necessary, supplies medicine, neurotransmitters, stimulants, etc. via a peristaltic pump, which are absorbed by the skin via the carrier substance dimethyl sulfoxide. The mask is also equipped with a head-up display, a CO gas sensor, an ultrasonic microphone, a voice changer, and maybe more. The goal of the project is to build a fully functional prototype and gather experience and ideas.

Details

A cyborg is a living being that has been technically supplemented or enhanced. It is thus a manifestation of human enhancement. This serves the increase human possibilities and increases human efficiency and thus the improvement and optimization of humans. Furthermore, by my own definition, a cyborg must have at least one bio-feedback in both directions that provides the cyborg with a superhuman ability.
I have chosen the head and thus a mask because most senses are located in the head and almost all important biomedical parameters can be measured at the head. Secondly, man has been using masks since the beginning of mankind. The oldest mask found is about 11,000 years old and comes from Israel. Remains of stone or metal masks were found - but drawings show that less durable materials such as cloth, plants, feathers, leather, or papyrus were also used to make masks. Masks are worn for very different reasons. For example, in the days before plastic surgery, masks were the best solution for veterans with faces scarred by war. And last but not least, almost every superhero or superheroine wears a mask.

The first thing I did was to make a plaster cast of my face because the mask has to fit very well. After drying, the inside of the cast was smoothed with Moltofill.

After multiple treatments with a release agent, the plaster mask was filled with epoxy-casting resin. The maximum filling height must be taken into account for the casting resin. The epoxy resin should cure very slowly. I chose one that takes at least 72 hours with a 2:1 ratio of resin to hardener. The sand bed serves to fix and dissipate heat.

The demolding was more difficult than expected. Despite the release agent, the plaster mold could not be removed. The plaster was then removed mechanically with a wire brush and a Dremel. Incidentally, cured plaster is hardly soluble in water. The solubility in water under normal conditions is only 2.1 g/l.

After the epoxy mold was filled, sanded, and painted with high-gloss resin spray paint, I applied release wax and then RESINPAL PVA release lacquer with a brush. The elevation on the forehead is for the microfluid pad.

The mask was then molded using the lamination process. I used two layers of woven 200g/m2 fiberglass mat. This was cut into 3cm wide strips. A paper cutter is best suited for this. The mask is very sturdy and weighs only 100g.

Then the attachments were designed in Inkscape, transferred to a 2 mm thick GRP sheet, sawed out, and attached to the mask with 2-component epoxy glue. They are used to attach the circuit boards, speaker, headband, and other peripherals. The cutouts for the mouth and eyes were also sawn out using templates. After curing, the mask was sanded and roughly filled. I used 2-component polyester putty for this. The best way to apply the putty is with your fingers, of course, protected by a nitrile glove. If you moisten your fingers with isopropanol, you can smooth the filler very well.

After more sanding, filling, and treatment with spray filler, the mask is ready for painting. I chose gentian blue (RAL5010) as the color for the mask, the attachments will be gold.

The weight of the mask has now increased to 300g. According to calculations, the finished mask will weigh about 450g, slightly less than the Oculus Quest 2 VR headset, except that the weight is better distributed in my mask.

The front side of the mask after painting:

Back side with glued-in microfluid pad. I used 2-component silicone for this, which was previously degassed in the vacuum chamber.

Partly assembled mask:

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Project Logs

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Shield design
M. Bindhammer • 03/25/2023 at 13:25 • 0 comments

Nothing fancy, mainly power and I2C distribution, a power bank anti-off, and an RTC for the doomsday clock.

Populated PCB:
Gas sensor
M. Bindhammer • 03/18/2023 at 11:01 • 0 comments

I use the MiCS5524 gas sensor, mainly because it is sensitive to carbon monoxide. Carbon monoxide is a highly toxic, colorless, odorless, and tasteless gas. The gas sensor can also detect other gases, but except for hydrogen, our sense of smell can detect and assign them with the exception of methane, propane, and iso-butane, which smell very similar. Here is an excerpt from the data sheet showing the resistance Rs as a function of the concentration of the various gases:

In the laboratory, a steady stream of carbon monoxide can be produced by dropping formic acid into warm, concentrated sulfuric or phosphoric acid:

That will help us to calibrate the sensor. In fact, we need a second point to calculate the straight-line equation. The sensor must be aged for 24 hours before any characterization or calibration. That is, it must run in clear air for 24 hours.

The two-point form of the linear equation is given by:

y is thereby the analogRead() value and x is the concentration. To calculate the concentration, we need to solve the linear equation for x:

The experimental setup for calibration was as follows. I used 96% sulfuric acid and 70% formic acid. As soon as the formic acid comes into contact with the sulfuric acid, carbon monoxide is produced:

The highest analogRead() value I obtained was 1005 in the carbon monoxide stream. In clean air, the analogRead() value is about 25. If we assume that an analogRead() value of 25 corresponds to 1ppm and an analogRead() value of 1005 corresponds to 1000ppm, we can plug the numbers into the straight line equation and get:

Of course, the whole thing is not particularly accurate, but I'll settle for it for now.
Biosensor
M. Bindhammer • 03/14/2023 at 11:27 • 0 comments

I use the MAX30102, an integrated pulse oximeter and heart rate monitor, as the biosensor. It can also be used to measure body temperature. Since the sensor has to lay very well on the skin, I cast it in 2-component silicone. After some experiments, it is possible to perform the measurements on the temple. Since the integrated LEDs can be switched on and off in real-time via the software and you can also change their brightness, machine learning can be applied.

Since we measure temperature at the temple, we need to convert it to body temperature. This chart from here is very useful for that.

To get a corresponding function, I entered the values in an Excel sheet, created a scatter plot, and chose a second-degree polynomial as a trend line. Excel then outputs the function automatically.
Extended hearing
M. Bindhammer • 03/12/2023 at 17:59 • 0 comments

The following circuit is not from me but from Burkhard Kainka. I have redrawn it and modified it a bit. So I use only one voltage and I added a MOSFET switch. It is basically a bat detector, but you can make many other noise sources audible with it. The interesting thing about the circuit is that an AM/FM radio chip (CD2003) is used in the core.

PCB layout top:

Bottom:

PCBs:
Digital voice changer
M. Bindhammer • 03/06/2023 at 12:57 • 0 comments

During my research, I came across the MSM6322 speech pitch control chip. It can be controlled very easily via a microcontroller. You can change the voice in real time, which is pretty cool. Since the chip is still available from some sources, I decided to use it. The first draft of the schematic looks like the following:

PCB layout:

Populated and tested circuit PCB. Works as desired:

The microphone holder consists of a custom-made part and parts of a cheap clip-on microphone. I soldered new wires to the electret microphone. I also made a sound box for the speaker.
Human-machine interface
M. Bindhammer • 03/04/2023 at 07:47 • 0 comments

As a human-machine interface, I use the APDS-9960, which can detect hand gestures and measure ambient light and colors. By the way, the sensor is also used in the Samsung Galaxy S5. I use the breakout board from Adafruit because it already has a level shifter integrated.
Substance supply system
M. Bindhammer • 02/26/2023 at 07:55 • 0 comments

Since the substances should be distributed over a large area and evenly on the skin, I designed a microfluid pad. For this purpose, a corresponding structure was built using ABS filament and then cast in 2-component silicone. Next, it was degassed by a vacuum chamber. After curing, the cast was placed in acetone. The acetone dissolves the ABS filament but does not attack the silicone.

After one day in the acetone solution, the channels were flushed using a small syringe to remove the dissolved acrylonitrile butadiene styrene. Then the silicone mold was placed in fresh acetone solution for another day, followed by a few hours in a 10% hydrogen peroxide solution. Finally, the silicone mold was rinsed several times using hot distilled water.

In addition to the microfluid pad, the system consists of a 6V peristaltic pump and a reservoir – a modified liquid bag for airplanes with a capacity of 30ml.

A three-way valve controlled by a servo would also be desirable. Then you could use two reservoirs and even mix substances. There are small and cheap medical three-way valves that are actually intended for infusions. It should not be too difficult to hack one of these.

Since the plug of the three-way valve is pressed in, it is somewhat stiff. The ES08 servo has too little torque for this. Therefore I took a Hitec HS-85 MG servo for the prototype. I used 3x2mm stainless steel tubes for the three ports, which were glued with 2-component epoxy glue. The two mounts were cut out of a 2mm GRP plate. These GRP plates are excellent for prototyping, as they are very easy to work with and extremely sturdy.

The microfluid pad cannot be placed directly on the skin, as the skin would close the channels. After experimenting with different materials, a cellulose sponge cloth turned out to be the most suitable. Using an appropriate hole punch, I punched out a disc whose diameter corresponds to the microfluid pad. This works best when the sponge cloth is damp.
Head-up display
M. Bindhammer • 02/25/2023 at 11:27 • 0 comments

As a head-up display, I use a 1.51-inch transparent OLED, with a 128×64 resolution and SPI/I2C interfaces. I drew the mounts in Inkscape, printed them out, spray-glued them to a 3mm thick GRP board, and sawed them out with a scroll saw.