AI-guided tenecteplase auto-injector

Clot-busting drugs work best within about three hours of symptoms, but the common ones run as IV infusions lasting hours, and at-risk patients often cannot reach a hospital in time. The brief: a clot-busting system an at-risk person can keep at home.

One rapid IV dose of tenecteplase, with dose and needle length prescribed by the patient’s physician; usable without phlebotomy training; a sterile single-use cartridge and needle. Verifiable requirements are in the table.

01Inject, don’t inhale or implant.

An EpiPen-style injector beat an implanted monitor, a public injection station and an inhaler on portability and cost.

02Size the needle to the patient.

A 22G needle (0.7 mm) comes in five lengths, 4.24–9.9 mm: a 2–6 mm skin-to-vein depth, plus 1 mm to the vein’s center, divided by sin 45°.

03Let the device see the vein.

Hemoglobin absorbs near-infrared light differently from tissue, so veins stand out. An RGB-NIR camera (450–800 nm bands) feeds VV-Net, a lightweight neural network already run on phones, and the app shows the vein map before the user fires.

04Keep the drug sealed.

A sealed cartridge sits inside an outer shell; a Luer-lock needle swaps out after each use.

I owned the vision subsystem: I chose the camera, based guidance on VV-Net, and proposed a micro-ultrasound probe and a needle-tip impedance check to confirm vein entry. I ran the risk assessment (injection accuracy, sterility, drug storage, user workflow), mapped the user’s steps to find use errors, and turned both into requirements. I also rebuilt the team’s concept in SOLIDWORKS 2025, as presented and as revised (see CAD).

A concept report and a team-built SOLIDWORKS 2024 model; nothing was built or tested. On review, its numbers disagreed (angles of 15–30°, 30–45° and 45°; 1 mL against 5 mL), the render’s proportions put the pen near 23 mm across, narrower than the 28 mm camera module, and stroke thrombolysis normally follows a scan that rules out bleeding, which no home device can do.

• Fix the angle at 30°, the upper limit in IV-insertion guidance: a 2 mm vein gives a 4.0 mm window along the needle, against 2.8 mm at 45°.
• Size a dual-chamber cartridge to the label’s 5 mL maximum; the drug ships as powder and must be used within 8 hours of mixing.
• Redo the pressure estimate (about 8 psi, not 1.5) and replace the camera body with a bare sensor.

Why the angle matters here: at the elbow, the median cubital vein sat 3.0 ± 1.8 mm deep and the brachial artery a median 3.6 mm beneath it in an ultrasound study, so a steep needle that passes through the vein’s back wall has little margin.

Inputs: 1 mL/s, the label’s maximum 5 mL bolus over 5 seconds; 22G regular-wall inner diameter 0.41 mm; viscosity of water, 1 mPa·s (assumed). The jet leaves the tip at about 7.6 m/s (Reynolds number ≈ 3,100), so the losses at each end of the needle dominate and the total is an estimate. The report’s 1.5 psi matches the viscous term alone for a thinner-walled needle.