The blood and gore of a crime scene doesn’t faze me in the least.
I’m unflappable under impassioned courtroom cross-examination.
But the idea of trekking through the icy impasses of an evidence freezer stops me cold. In fact, the mere thought of opening the freezer door to locate the next item of evidence is absolutely chilling!
If you haven’t struggled to locate freezer-based evidence in order to meet a processing or reporting deadline, raise your hand.
Anyone…?
For those of us who know the stressors of evidence cold storage all too well, you may want to warm up to the idea of adding automated storage systems to your automated workflows.
I continually advocate for a holistic rather than plug-and-play approach to automation, because the latter doesn’t account for inefficiencies or pain points associated with a given task. Using the holistic approach, each forensic lab is able to develop a specific plan to create an automated ecosystem that drives process efficiencies and reduces backlogs and turnaround times.
The plan starts by physically mapping your workflow, people, and all the other elements that go into processing casework and/or databasing DNA samples. You might be surprised at what you uncover in the details.
For instance, manual pipetting may be an obvious time-consuming pain point, but the total time spent searching for each sample in a freezer may be less obvious until you see the process fully mapped out. By the same token, it’s generally known that variability and errors in manual pipetting performance can ultimately compromise data integrity, but a data threat can also arise as samples are exposed to compromising freeze-thaw cycles. I love having a frost-free freezer in my house – no more using a hammer and screwdriver to dig out my favorite frozen treat from its icy prison! But, alas, this 21st century self-defrosting convenience cannot be used in a forensic lab, because it creates a series of freeze-thaw cycles that compromise sample integrity. And what about your workmates? Freeze-thaw cycles occur in freezers without the self-defrosting feature each time an analyst rummages through freezer contents or keeps the freezer door opened for prolonged periods.
Once you have a clear and documented process flow, it’s easier to integrate an automated storage system into your workflow. It can start with the lab’s current laboratory information management system (LIMS), where analysts can quickly create automated pick lists without the risk of transcription errors.
Pick list information is sent to an automated storage system that literally “picks” the samples for the analyst while (s)he has time to focus on other tasks or even grab a coffee. Automated storage systems are available in temperature controlled, refrigerated, and frozen ranges to support short-term active casework or long-term evidence storage in compliance with best practices and local jurisdictional requirements.
Automated storage systems scan sample tube barcodes, containing sample and case ownership details, to verify and document that the correct sample was retrieved. Information on the sample’s storage history and the storage system’s performance is continuously monitored and displayed, and these data may be stored and added to the relevant case file.
In the integrated hands-free system, the racked samples are then automatically handed off to a liquid handling workstation that can process samples in a batched, high-throughput manner to increase processing efficiencies. The liquid handler may be pre-programmed with methods specific to your preferred assay chemistry, and fine-tuned to your lab’s specifications.
The barcoded samples are scanned again to verify correctness, maintaining an unbroken chain of custody, and automatically moved around the deck of the liquid handling workstation during execution of the analytical method. The workstation deck includes peripheral items needed to perform pre-PCR or post-PCR steps, including heaters, shakers, plate sealers, thermal cyclers, and other items as necessary. In addition to eliminating many user-based errors, this setup removes variability from poorly defined steps like “mix thoroughly”.
All sample movements are tracked. This information and other run-specific details are included in a standardized output file format that may be sent to the LIMS and included in the case file, cutting down on report writing and review time.
And, as manual involvement and manual verification checks are not necessary while samples are being processed on the robot, analysts can continue to attend to other activities or, perhaps, have another coffee!
It’s worth noting that both the automated storage system and liquid handling workstation include user permission levels and lockout controls to prevent accidental or unauthorized access.
Once the samples are processed, they may be manually removed from the workstation for further downstream processing or automatically logged and returned to the storage system to complete the cycle.
So, if locating backlogged evidence leaves you cold, warm up to a holistic approach to your forensic laboratory ecosystem. A process flow that integrates automated storage and liquid handling systems offers increased piece of mind, throughput, and substantial labor savings while also strengthening both sample and data integrity, evidence documentation, and confidence in your results.
“Dr. Miller's Unfiltered Tips" is authored by Dr. Kevin Miller, Senior Market Segment Leader, Scientific Content Manager at Hamilton Company in Reno, NV. After earning a Ph.D. in Molecular Anthropology from the University of Cambridge, Dr. Miller actively engaged in promoting, researching, and furthering forensic science advances, and remains committed to this endeavor today. In his words, "I am a forensic geneticist who, like most forensic folks my age, fell into the field from somewhere else (I was digging up Viking remains in the Northern Isles of Scotland, but that is a completely different story) and stayed … at least until I brought automated liquid handling to my laboratory. Now I work with automation engineers, and try to make sense their world for the people in mine. I’ve picked up a lot of tips, and given away a few. Sometimes useful. Always unfiltered."