. Overview

With the purpose of making our biological machine more convenient to use, we design a hardware specifically for our project. This hardware consists of 3 layers. The first layer is a great warehouse that stores fresh culture medium and inducers (IPTG, ATc and other smell molecules we intend to memorize). The second layer is an incubation chamber for bacteria incubation. Flexible tubes are used to connect the first layer and the second layer for the use of adding the inducer. Cameras are set on the second layer to monitor the reporter signals generated by the bacterial cells. Blenders are equipped inside the chamber for bacteria incubation. The third layer is approximately a waste box used for collecting waste fluids from the second layer for the biological safety issues.

Figure 1. Different views of our hardware.

. Design & Material

 o  Framework

The construction of the framework was designed on CAD 2019 with the help of Creo 4.0. We decided to use PLA (Polylactic acid) as our 3D printing material. Most of the framework elements are printed by 3D Printer owned by HZAU College of Informatics, others are produced by Laser Cutter. Grater, Padsaw, Gimlet and Sander are used for rough and precise processing. Steering engines (SG90) and their arms, which are fixed by these Bolts and Nuts with the corresponding Roller, work as the Gears engaged.

And the PVC (Polyvinylchloride) flexible tubes are glued on the framework by Mounting wax. All connection sites linked to natural environment will be covered with 0.22μm filter.

 o  Automated devices

The output voltage of Polymer Lithium-Ion Battery (PLB) is 12V, but the power is linked to a Voltage regulator module (AMS1117-3.3V) which turns it down to 3.3V to support the Single-chip micro computer (STM32F103C8T6).

Other elements like the Steering engines, Electric Machinery (GA12-N20 150rpm), Needle Cameras (Esp32-cam), Blue Tooth adaptor ( TLSR8266 ) are supported by another Voltage regulator module (LM2596S).

The program is coded and flashed to the single-chip microcomputer by Keil 5. And the Electronic circuits are stored in the Single-chip microcomputer as well.

Blue tooth dongle is used for remote controlling by our user and their mobile devices.

. Process

Boot : Make sure that the Boot switch is on the hardware.

Start Recording :Our users can manage this sensing process simply by tapping the Start Recording icon on their devices. The steering engines will start to work and link the incubation chamber with the incubation medium layer (a.section in Video 1) and the waste collection layer (b.section in Video 1) by flexible tubes. This process is designed for draining the dead bacterial cells and adding new culture medium in an autonomous way, thus this programme is set to repeat periodically.

This operation will link the incubation chamber with the smell storage chamber (for example : benzyl alcohol), once steering engines work. Meanwhile the Blender will be working.

Video 1. Start Recording

Detection : Our genetically engineered E. coli senses the specific smell and it will activate blue chromoprotein which turns the medium into blue visually. And this phenomenon will be captured by our needle cameras, if the View status icon is tapped. The monitoring connection IP is required as code (showing in the Video 2).

Video 2. View Status

Reproduce : Same controlling routine as before, tapping the Reproduce icon will release the IPTG from its layer to the incubation chamber (showing in the Video 3), the switch turns on as the steering engine arms move.) And IPTG induces our reproduce circuits to synthesize the exact smell in our genetically engineered E. coli.

Video 3. Reproduce

Sensation : A manual switch is designed on purpose for our users to smell the reproduced smell.

Erasure : The last icon Erase is for clearing the current smell information that has been remembered in our genetic circuits. Tap it and the ATc will be led to the incubation chamber through a flexible tube (showing in Video 4). This chemical gets the power to switch on our resetting circuits. After being induced by ATc, the whole system will turn off automatically in a few minutes.

Video 4. Erasure

Confirmation : Through the needle cameras, our users are capable of confirming whether the former smell information is cleared thoroughly. If the color of incubation medium become normal again or the color is much lighter than before, it proves that our genetic circuits successfully work.

. Expectation

In our project, we expect to build up a system of sensing and reproducing various smells, working as a database. By referring to different research articles, we can collect all the information of other smells with different sensors and circuits to reproduce them. 96-well plates are illustrated to be the most ideal container to realize this expectation. We design a concept that soon we may come up with this stable, safe and convenient equipment, with all necessities to run properly.

Figure 2. Draft of our ideal device.