Collaborative Robot Precision Task in Medical Microbiology Laboratory

Abstract

This study focuses on the feasibility of collaborative robot implementation in a medical microbiology laboratory by demonstrating fine tasks using kinesthetic teaching. Fine tasks require sub-millimetre positioning accuracy. Bacterial colony picking and identification was used as a case study. Colonies were picked from Petri dishes and identified using matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry. We picked and identified 56 colonies (36 colonies of Gram-negative Acinetobacter baumannii and 20 colonies of Gram-positive Staphylococcus epidermidis). The overall identification error rate was around 11%, although it was significantly lower for Gram-positive bacteria (5%) than Gram-negative bacteria (13.9%). Based on the identification scores, it was concluded that the system works similarly well as a manual operator. It was determined that tasks were successfully demonstrated using kinesthetic teaching and generalized using dynamic movement primitives (DMP). Further improvement of the identification error rate is possible by choosing a different deposited sample treatment method (e.g., semi-extraction, wet deposition).

Keywords: MALDI; colony picking; kinesthetic teaching; learning from demonstration; mass spectrometry; sub-millimetre accuracy.

Figure 1

Overview of the experiment setup (left) and the end-effector tool (right).

Figure 2

Overview of the experiment workflow: an image of a petri dish acquired with RGB camera (a), a 3D model of the selected bacterial colony generated from 2D laser profiles (b), the bacterial colony picking process (c), and the bacterial colony deposition process (d).

Figure 3

Using DMP to generalize demonstrated trajectories of the picking (left) and deposition (right) task. In order to demonstrate the quality of generalization, the end position of the picking process is modified, whereas both the start and end position are modified for the deposition process.

Figure 4

Overview of the picking process. Multiple different colonies are plotted before (top) and after (bottom) the picking process.

Figure 5

The contact force between the end–effector needle and MALDI target plate and the corresponding compensated z position (left), and an image of deposited colonies on the MALDI target plate after being covered with the matrix solution (right).