← Research / Project 03

A Rotational Redesign of a Valve-Based RNA Amplification Device

VLEAD runs lysis, paper-based RNA enrichment, and amplification inside one device. The published version works, but it works in a lab: milled polycarbonate, adhesive tape, and a slide that has to be lined up by a trained hand. This redesign turns the whole sequence into a twist.

Fig. 1 Bench test of the current build, dye standing in for reagent. Turning the top advances from one reagent to the next, so the operator doesn't need to know the sequence, they just twist.

Affiliation

Principal Investigator: Prof. Z. Hugh Fan
Institution: University of Florida
Department: Mechanical & Aerospace Engineering
Group: Interdisciplinary Microsystems Group
Status: Ongoing

What VLEAD does

VLEAD is a valve-enabled device that carries a sample through chemical lysis, paper-based RNA enrichment, and nucleic acid amplification without the operator pipetting between steps. The reagents are held in separate wells and the paper is moved between them, so the order of operations is built into the mechanism rather than into a protocol someone has to follow correctly.

The version published by the Fan lab establishes that the chemistry works in this format. What it does not do is survive contact with a non-specialist. It is assembled from milled polycarbonate and adhesive tape, and the paper is advanced by sliding one layer across another, which means the person running it has to both align the layers and judge when a step is complete.

Underneath the packaging it is a low-cost platform for sequential reagent release using microfluidic ball valves. The goal is to run chemical lysis, RNA enrichment, and nucleic acid amplification as an ordered sequence inside a single device, enabling multiplexed detection of HIV, dengue, and Zika without an operator pipetting between steps. It is the same instinct as my work in London: replace a procedure that currently requires a trained hand with something the device does by itself.

What I changed

I rebuilt the device around rotation. The paper is clamped in a screw fitting and reagents are released sequentially due to the geometry. The milled polycarbonate and the tape are both gone, replaced by printed parts that assemble without adhesive.

The point of the redesign is real world deployment. A device that needs a trained hand is a lab instrument no matter how good its chemistry is, so most of the design effort has gone into removing the places where an operator can get it wrong rather than into the assay itself.

The design change

Diagram of the sequential reagent release platform: buffer wells with ball valves above a mixing unit and paper detection unit, plus the portable heater and microscope stand — **Fig. 2** The sequential reagent release platform. a Four buffer wells, each sealed by a bearing ball, sit above a mixing unit and a layered paper detection unit. b A pin displaces the ball and opens a gap, releasing one reagent at a time in a fixed order. c The portable reader: heater, integrated circuit, batteries, and a microscope on a 3D-printed stand, sized to run the assay away from a lab bench.

The reagent wells sit in a single printed disc. Each well is a hemispherical pocket with a through-hole at its base, and an alignment pin sets the disc's orientation relative to the rest of the stack, so the sequence of reagents is fixed at assembly.

Below it, a threaded cap carries the paper. Tightening the cap clamps the paper against its seat, and turning the assembly is what dispenses the next reagent. Everything that used to be a tape joint or a hand-aligned sliding face is now either a thread or a printed feature.

CAD render of the reagent disc, four hemispherical wells with through-holes and an alignment pin — **Fig. 3** Reagent disc. Four hemispherical wells, each with a through-hole at the base, and an alignment pin at the rim.

Sectioned CAD view of the paper holder showing the internal slot above the threaded stem — **Fig. 4** Section through the paper holder. The cut shows the internal slot the paper seats into and the port through the threaded stem beneath it.

CAD render of the rotating cap with its threaded boss and alignment pin — **Fig. 5** Rotating cap. The threaded boss engages the body below, and the pin registers against the disc so rotation indexes rather than free-spins.

CAD render of the threaded housing with an outlet port at the base — **Fig. 6** Housing. Internal threads take the cap, and the port at the base is the outlet the sample passes through.

Where it stands

The current build has been run on the bench with dye standing in for reagent, which is enough to show that the rotation indexes cleanly, that the clamp holds the paper, and that liquid goes where the geometry says it should. It is not yet enough to say anything about the assay. Running the real chemistry through the redesigned device, and doing it enough times to speak about repeatability, is the next step.

← Previous project Engineering projects →

Contact

Email: noah.haeske@ufl.edu
Phone: 407-705-9895
Resume: Download PDF