Automated Blood Smearing Machine for Distributed Clinical Hematology

Spring 2019 Team 18

Cindy Ayala
Marco U. Colón
Christopher Patrick
Kevin Tsao

Sponsored by Dr. Elizabeth Broome and James Kirk, Ph.D.
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Complete Final CAD of Wick-N-Slides Design 


Blood films, or peripheral blood smears, are used to diagnose different conditions affecting blood cells. Blood smears are typically created by depositing a droplet of blood onto a microscope slide and wicking the blood across the bottom a flat blade and spreading the blood across the slide to create a thin, evenly distributed monolayer of blood cells that can be individually imaged under a microscope. Currently, few blood smear making devices are on the market, some of which cost up to $30,000. A more affordable alternative would enable small clinics and labs to automate their own smears and obtain consistent results.


The main objective of this project is to create an automated blood smearing device that performs as well as more expensive commercial models. The device must create smears using animal blood at different speeds using a disposable smearer in lieu of a cleanable one to reduce complexity and cross-contamination. Additionally, a simple-to-use user interface should allow the user to manually load a slide and deposit blood then hit a button to initiate the smearing process. 

Flowchart Overview

Final Design

The final device incorporated a custom made smearing unit designed with one-time-use smearing blades to minimize cross-contamination between smears. Additionally, the device had a small drying fan that ensured the slides were completely dry before the user removed them from the device. The slide moved from one location to the next by the motion of a belt-driven linear guide system. A PCB and electronics enclosure ensured minimal safety hazard to the user and a simple graphical user interface (GUI) was implemented to further improve user experience. 


The device successfully created consistent smears, as seen in the image below. One important factor of blood smears is the smearing length and, as shown in the image, the smears were consistently similar in length. Additionally, the smears displayed similar characteristics to those created with professional smearing devices, including a round "corona" end and a smear gradient with thicker film at the top and progressively becoming thinner as the smear ends. One downside of these smears is the chattering marks seen throughout all the smears displayed by discontinuations in the smears. These defects were caused in part by a vibrating system due to electrical issues in the linear guide system. However, despite this flaw, these smears are indicators that this device can function as an alternative to other smearing devices. 

Staining and Imaging Results for Each Sample (From Left to Right: S1, S2, S3, S4, S5)