Introduction
Hardware design is a crucial part of our project. Our team aims to produce L-lactate from recombinant E. coli as a lure to attract bed bugs. Currently, many pest control companies are present in Hong Kong. However, not all households have the ability to afford bed bug elimination services, or rather the treatments are time-consuming and inconvenient, leading to many unresolved infestations. With our hardware device Debugger, we hope to produce an affordable and user-friendly device which could effectively prevent bed bug infestations.
Debugger Prototype 1
Our first approach was to eliminate bed bugs as quickly as possible by attracting and trapping them in a device. Based on research of bed bug behaviors, we discovered that the bugs can only spread by travelling on carriers from one point to another[1]. When the insects are first introduced to a new place and develop into a large-scale infestaion, we assume it is possible to make use of L-lactate to attract and kill all of the bed bugs.
The Model Design
(Fig.1a, Debugger Prototype 1)
(Fig.1b, Debugger Prototype 1 exploded-view)
Debugger could be used right after visiting places with high risk of bed bugs infestation. Multiple kits are placed around corners of the room and the lure from Debugger could attract them to the device. When the bugs attempt to approach the lure, the bugs fall into the indented well. The well is designed to have a smooth surface which bed bugs are unable to escape by climbing up. If users spot bed bugs trapped in the well, the well could be removed and the user is advised to put the well in 70℃ hot water for 10 minutes to ensure all the bed bugs are killed. The well could later on be connected back to the kit for repeated usage, while the lure could be replaced upon depletion.
Feedbacks from bed bug specialist
During an interview with Mr. Francisco Pazos from ChinChex, a pest control specialist, our team presented the idea of Debugger Prototype 1 in hopes for feedback regarding practical usages and difficulties that will be encountered during pest control. Mr. Francisco stated that if the trap is not immediately applied after the bed bugs got into the home, the trap could not exterminate 100% of the bed bug population. This is due to the high reproduction rate of bed bugs, if not all bed bugs are attracted to the kit, the remaining ones would reproduce rapidly, resulting in recurring bed bugs infestation.
Mr. Francisco also provided us some insights on the usage of Debugger. Currently, there is no chemical that could attract the whole bed bug population. In large areas such as houses, the attracting effect would be minimal. Therefore eliminating all bed bugs through attraction would not work.
From the feedback of Mr. Pazos, our team concluded our elimination approach may not be possible, as the trap cannot be applied for residential places. We had to find a new approach to prevent bed bug infestation.
Developing Debugger Prototype 2
Currently, services regarding early detection of bed bugs could rarely be found. We further investigated the nature of bed bugs, in which we found out that bed bugs prefer hiding in confined and small spots, such as furniture, luggages and bags. Due to the fact that bed bugs can only spread by ‘hitchhiking’ on carriers, our team proposed the idea that early detections for bed bugs could be done on luggages. Visual inspection for bed bugs are difficult because of how they could hide in different small gaps, therefore we created an attraction kit that could be used to identify if any bed bug is present in the luggage. The kit could be put inside the luggage after the user returns from a location with high risk of bed bug infestation, where the lure evaporates within the confined luggage and attracts the bugs to the kit’s harborage. If any bug is found inside the kit, the user could deduce that there may be bed bugs present in their belongings which needed to be treated or sterilized immediately before any bug could spread out.
(Fig.2a, Debugger Prototype 2)
(Fig.2b, Debugger Prototype 2 side views)
(Fig.2c, Debugger Prototype 2 bottom view)
(Fig.3, 3D model of Debugger Prototype 2)
The portable Debugger Prototype 2 consists of the diffuser harborage and a liquid container to store L-lactic acid. The harbor includes multiple layers of woods, cardboards and chromatography papers. The wood provides support to the diffuser and the cardboards provide small holes for bed bugs to stay in. L-lactic acid, stored inside the container, is absorbed by pieces of chromatography paper and evaporates from the paper to attract the bugs.
(Fig.4, layers of the diffuser)
We chose acid-resistant polycarbonate to produce the container. Before usage, a film plastic is removed to allow entry of the diffuser, which safely covers the connection parts. This system features a non-liquid dispersal mechanism that prevents leakage of the acidic solution, ensuring absolute user safety while delivering a highly effective, early-stage intervention kit for bed bug infestation prevention.
After usage, users could check the detection kit for bed bugs from the holes of the harborage with a flashlight. The presence of bugs inside the detection kit may indicate that the luggage could contain more of them, in which sterilizations could be done to the luggage immediately before the bugs spread in the house. A zipper bag is provided for users to put the used diffuser inside to prevent leakage of lactic acid and escape of bed bugs. If the container still has remaining L-lactic acid, users could insert a new diffuser for repeated usage.
Our team made a user manual to ensure clear and safe usage of Debugger as our kit includes L-lactic acid which is irritative to skin when contacted.
Future directions
Throughout the development of Debugger, our team believes that our implementation should be easily accessible in order to truly stop the infestations of bed bugs. From invaluable feedback from experts to the whole designing process, we always make adjustments to improve Debugger as a whole.
From the feedback of Mr. Pazos, we understanded more about the nature of bed bugs, and how their traits could affect the design of Debugger, which we would later implement Debugger inside luggages for greater cost efficiency to prevent bed bug infestation.
For our latest prototype design, there were still some enhancements we wanted to make, but due to technical issues and limited resources, some could not be achieved at the current stage:
- The size reduction of Debugger:Debuggers could be manufactured smaller in size with lower cost, and multiple kits could be used at once inside a confined space to increase successful detection rate.
- Materials:The diffuser could be made from more cost effective materials, such as recycled cardboards for harborage. For repeated usage of the liquid container, a lid is required to cover it. Other than the plastic film, we aim to use materials which are more environmentally-friendly.
- Leakage:Slight leakage occurs as testing liquid (water) seldom leaks through the holes of chromatography paper, and liquid seeps through the four edges of the container when put sideways. For future design, rubber rings could be added in the interior to prevent leakage.
- Outlook:The current model utilizes hot-melt adhesive to connect different parts, leaving unpleasant looking stains. In the future, we would make use of silicon rubber to make a cleaner look.
- In the future, we hope the improved Debugger could also be used by the lodging industries. Hotels or accommodation services could apply Debugger in rooms to help detect the presence of bugs.
Reference
[1]Doggett SLDwyer DE, Peñas PF, Russell RC.2012.Bed Bugs: Clinical Relevance and Control Options. Clin Microbiol Rev 25:.https://doi.org/10.1128/cmr.05015-11