Power

All of the OpenScope electronics consume 10 times less power than just the arc lamp of a typical lab-bench fluorescence microscope. OpenScope can run on battery for up to 12 hours. This time was estimated on the basis of a power consumption analysis. To power OpenScope from batteries up you will need the MoPi power module for Raspberry Pi and two 9V batteries. We recommend replacing the single 9V cell for a series of 6 1.5 AA batteries for best performance. For this purpose, you can 3D print this battery holder.

Cleaning

We are aware that an item placed into the sterile environment of an incubator can cause contamination to any living samples. But this will not happen with OpenScope, if you simply spray it with isopropanol before using. Isopropanol (propan-2-ol) is safe for the PLA and the electronics. Never attempt to use methanol (this will make the PLA soft) or acetone (this will dissolve the plastic).

Stage Drift

In order to perform time-lapse imaging, the digital microscope must be left capturing images for long periods of time. However, most microscope stages exhibit a drift, which causes the sample to move during the experiment. OpenScope is not an exception, especially given the fact that the stage is made of plastic. In order to characterise our prototype brightfield microscope, an experiment was set-up to record the movement of points (fiducial mark) on a slide over a period of roughly 16 hours. You can see our experimental findings below. In spite of the drift, OpenScope is still suitable for time-lapse imaging, if used in conjunction with software which is capable of point tracking.

Optics

The imaging system of OpenScope is based on a Raspberry Pi camera. Inverting the lens of the camera converts it into a microscope objective. Read why in the document below. With the Raspberry Pi Camera, resolution of 4 μm was achieved, but then sub-micron resolution was reached with a commercially available ball lens (from Comar Optics). The objective of OpenScope is 3D-printed, like the rest of the parts, and the spacing between the CCD and the lens in it was optimized for the lenses we used. However, this is an easily modifiable parameter in our .scad design files, which means that anyone can adapt the objective they use for the magnification, field of view, and resolution they need.

Strength

Bending tests were performed to confirm the strength of the OpenScope stage. The material used to print it, PLA, turns out to be 4 times stronger than the alternative material, ABS, and 13 times stiffer than it. We also explored how different orientation of the object during 3D-printing affects its strength, and took this into account when putting together the OpenScope print files. Moreover, it was confirmed that the plastic is not subject to plastic deformation due to weight-loads that the OpenScope stage will typically have to bear. In short: you can put OpenScope in your backpack and not worry about it getting broken (we tried this, too). The detailed report from the strength testing experiments can be found below.

Multiple Microscopy Modes

OpenScope supports three different modes of microscopy:

• brightfield: in this simplest setup, the sample is illuminated with a white LED from below

• darkfield: this mode requires mounting of a 3D-printed darkfield tube underneath the stage (for an explanation on how darkfield works, see the document below)

• fluorescence: for this mode, we have carefully developed the epicube, which houses the camera CCD, the lens, the 3 filters required, and the illuminating LED (for more information on how fluorescence works, see our Modeling page)

Switching between these modes is as simple as just swapping between the different modules, and the different modes of illumination can be controlled through the WebShell.

Movement Precision

When designing the OpenScope stage, we have taken advantage of the flexibility of the plastic. The flexure mechanism allows the stage to move horizontally very smoothly, and all care was taken to provide just as smooth vertical movement. Using screws to control the mechanics provides an extra degree of smoothness. In addition, the microscope can be motorized for complete remote operation (again, through the WebShell). We used cheap low-power (operating at 5V) stepper motors, which are still highly accurate: they are geared to 513 steps per revolution, which translates into approx. 0.6μm movement of the sample per step. For the detailed analysis, see the document below.

Affordable Price

The total cost of OpenScope is determined mainly by the price of the electronics used, given that the plastic 3D-printed components round up to 2£ (100g of PLA). You will also definitely need the Raspberry Pi camera(15-20£), the Raspberry Pi itself (25£), an Arduino PCB, some LEDs. On top of that are some optional components: motors if you want to control openscope remotely; filters - if you will image fluorescence. To figure out which components you need and which not, for your own OpenScope, consult our Make Your Own page. You can download the full Bill of Materials below. The total price stays in the range 50£-100£, which is two or more orders of magnitude lower than the price of the commercial lab microscopes.

Size & Weight

The plastic stage of OpenScope weights just over 100g, and the height of the whole assembly is just over 6cm in height. Together with all of the accompanying electronics, it is easily transportable in a 13x13x13 cm box.