Designed in association with B&W Tek-Metrohm
QTSampler is a rapid, non-destructive analyzer for pills and capsules. It uses Transmission Raman Spectrometry to perform quantitative pharmaceutical analysis.
The product is among the first portable transmission Raman spectrometers on the market for pharmaceutical product analysis, as opposed to large batch analyzers, such as Agilent TRS100. Thus, the mechanical design of the product is challenging and requires some unconventional thinking.
Following the described needs in Function Requirement Specification (FRS), I designed
1) Mechanical- The pill sample loading station is guided by a gas spring and two linear ball-bearing slides, with a push latch enabling the click-and-lock function. Thorough force balance and degree of freedom (DOF) analyses were conducted to ensure a smooth operation. With detailed design and precise calculations, the mechanics functioned seamlessly during the first test on the prototype trial, eliminating the need for a mini-prototype and significantly reducing design time and cost.
2) Opto-Mechanical- Precise optical alignment is critical in spectrometry. "Designing with alignment in mind" is the key, as tight part tolerances and stack tolerance analysis alone are insufficient for achieving the required accuracy. Various design features were implemented to provide the necessary degrees of freedom for the assembler’s final fine-tuning, from determining the targeted focal point location to small details like drilling holes for epoxy flow. Each design element directly impacts the quality of the received optical signal.
Fiber optic wiring is a key optical consideration in this design. The space must be compact for portability while ensuring cables remain above the minimum bend radius within their protective casing. Carefully mapping cable routing in the CAD model ensures a strong signal and clean transmission while keeping the product size minimal.
It was soothing to know that the optical signal returned following the FRS requirement with the first prototype trial.
3) Aesthetic– To give the product a sleek, tech-inspired look, I used silkscreening, electroplating, and bead blasting. There was a lot of back-and-forth with the vendor to make sure the textures and finishes matched the vision the team had in mind. Some parts feature gold plating and mirror finishes as well to meet optical performance needs.
Fun fact: there was actually a blue version of QTSampler as well, intending to match the company’s theme color. The primary white Design won out—its clean, premium look reminded the team of Apple products and was a hit with management. “The younger generation is bringing a new aesthetic to the business,” they said.
All in all, it was a great experience being the mechanical engineer on such an innovative product. Bringing the concept to life, from sketch to final test, wasn’t easy, but it was incredibly fulfilling. I could go on forever, but I think this gives a good glimpse into the design of QTSampler. Our product manager at the time, Parag, provides a detailed demonstration of the product here.
If you're curious to know more, feel free to reach out! :)
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