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Engineering, regulatory and clinical insight from the RhythmRx team. Practical guidance on device development, quality systems, and getting cardiac technology from concept to clinic.

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Viscosity Is the Design Constraint Nobody Budgeted For: Engineering Subcutaneous Delivery of High-Concentration Biologics

Formulations above 200 mg/mL frequently exceed 20 cP. Divya Menon on why viscosity quietly governs the entire injection device design space.

Divya Menon

Dose Is Not What You Set. It Is What the Tissue Receives.

Thirty watts for thirty seconds is not a dose. Vikram Sethi on delivering therapy through a variable, partially observable patient.

Vikram Sethi

Sensitivity and Specificity Are Not Enough: Why Diagnostic Devices Fail Outside the Laboratory

A test with 95% sensitivity and 95% specificity produces mostly false positives at 1% prevalence. Dr. Shalini Krishnamurthy on what performance claims leave out.

Dr. Shalini Krishnamurthy

Two-Thirds of 510(k)s Get a Deficiency Letter. The Deficiencies Are Almost Never About the Device.

Around two-thirds of 510(k)s receive a deficiency letter, and almost none of the deficiencies concern whether the device works.

Rohit Nambiar

A Device Investigation Is Not a Small Drug Trial: Designing Clinical Evidence That Satisfies CDSCO, FDA and MDR

No placebo, no blinding, an operator who improves mid-study, and a device that changes. Dr. Ananya Chatterjee on designing device trials that survive review.

Dr. Ananya Chatterjee

Your Supplier's Quality System Is Now Your Quality System: Purchasing Controls Under the QMSR

Supplier controls appeared in roughly half of all device warning letters in 2025. Priya Deshmukh on what purchasing controls actually have to do.

Priya Deshmukh

The Prototype That Cannot Be Built Twice: Design Transfer Is a Statistics Problem, Not a Paperwork Problem

A design that works at n=10 meets a process that must work at n=100,000. Aravind Venkatesh on why design transfer is a statistics problem.

Aravind Venkatesh

Design Is Still the Leading Cause of Class I Recalls. The Failure Almost Always Starts at Design Inputs.

Recall data shows device design causes roughly 55% of Class I recalls. Karthik Raghavan explains why the failure almost always starts at design inputs.

Karthik Raghavan

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