This week we took apart an Optical Coherence Tomography Device manufactured by BioMedTech.
The machine was contained inside a rectangular box with an adjustable handle which pivoted and locked in place to make it easy to travel with the box. There were multiple ports for power, control probe, and fiber probe. The latter likely attached to external probes to take pictures of the internal structures of the eye. On the back there was a usb-b port to transmit this data to a computer and a footswitch port which likely attached to an operating pedal.
We started by unscrewing the screws in the front and back panels using Phillips head screwdrivers. The majority of this machine was fastened together using traditional phillips head electronics screws. The back panel had footrests as extra padding, suggesting that the machine was commonly rested on the backside. The extra handle grip also suggests that this device was built with travel in mind.
After taking out the screws, the top panel was able to be removed, exposing the vital inner electrical components which make up the meat of the machine.
Pictured is the top panel which was welded to the wires connected to the electrical components. This connection had to be cut using wire cutters and likely served as a grounding wire.
We disassembled the handle by popping off the plastic covering using a small screwdriver and exposing the locking mechanism (left). We popped the spring out and used an allen wrench to unscrew the handle. What remained (right) shows an aluminum piece which acts as a locking mechanism for the handle to secure it after turning. The remaining pieces were removed using a Phillips screwdriver.
We then removed the back panel and the supporting beams on the top. Across the supporting aluminum beams, there were 4 adjustable interior brackets which used snap joints to click into the aluminum beams and their orientation could be customized to organize the PCBs. The majority of the structural components were machined by extruding aluminum, which was evident as we examined the parts. This fabrication method is known for its strength-to-weight ratio, its cost-effectiveness, and its sustainability as it can be made from recycled materials. All of these factors make it a good choice of material for this optical coherence tomographer.
The printed circuit boards (PCBs) were removed by detaching pin and socket connections and unscrewing them from the base boards. There were also a number of spacers throughout the assembly which helped space out the PCBs and allow proper airflow throughout the machine.
A few wires had to be cut to remove the PCB from the housing because they were directly connected to the outer panels. Funnily, we even found a PCB that was attached to a USB using hot glue
Example PCBs, likely custom made and sautered by hand
The back panel was hard wired with multiple wires which connected to various PCBs. These had to be cut to remove the back panel. There was also a cord connecting the front and back panels that had to be cut because the ports could not be removed from the panels.
The optical system (below) consisted of multiple focusing lenses and a long thin optical fiber wrapped MANY times around a circular organizer made of plastic. There were a couple PCBs screwed onto the board as well. Interestingly, the weight of the optical components only accounted for 19.1% of the total weight of the machine. Although these optical sensors were probably the most expensive and integral part of the machine, they were relatively light compared to the outer casing and PCBs which were the other two main components by weight. In fact, just the outer panels made up 44.2% of the total weight of the machine. Although they were probably the simplest and cheapest parts of the machine, their extra weight must have ensured safe casing of the valuable and delicate inner components, especially through transit.
Top of optical system
Bottom of optical system (left), lens (right)
Custom L-bracket (left), tried to unravel optical fiber (right)
We found a few homemade custom components throughout the machine, such as the custom L-bracket shown above. Most of the components were most likely custom made for this machine, especially the PCBs and optical system. Given the custom parts, it does not seem likely that this machine was designed with recycling in mind. It was really cool to see a unique machine that engineers had designed and built in an almost haphazard way. It is very different from modern electronic devices, many of which are carefully designed and organized to minimize open space and extra wiring. For machines that are not mass produced (like this optical tomographer which probably had less than 10,000 produced), it is less important for the assembly process to be optimized. This is certainly true for this machine, which we could tell was put together with care by technicians. We also noticed that the front panel was secured with Torx screws, which are known to have better torque than a phillips head and are less available to the public. This design choice may signify that the front panel was meant to be opened often by technicians to access the inner components but also to prevent laymen from attempting to open the device. This machine seems to be designed to be taken apart by technicians in case of repair, suggesting that it would have been fixed instead of discarded and replaced.
Cleaned workspace!
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