Why biosensor manufacturers need to think about the Biological Evaluation Report (BER) early

For any diagnostic or medical device that comes into contact with the body, biological safety is demonstrated through a structured, evidence-based framework. This is known as the Biological Evaluation Report (BER), which is the central document regulators rely on to understand how a manufacturer has assessed and mitigated biological risks.

For biosensor developers (especially those innovating rapidly or working with emerging materials), planning for the BER early can eliminate costly delays, prevent repeated testing and reduce uncertainty throughout the development process. As device architectures become more complex and contact modes more varied, the BER becomes as much a strategic tool as it is a regulatory requirement.

This article outlines what the BER is, why it matters and how early planning strengthens both timelines and outcomes.

What the BER is, and why it matters

The BER explains with scientific justification why the device is safe for its intended clinical exposure. Regulators rely on this document because it demonstrates that the developer understands the biological risks associated with their design and has addressed them systematically. A strong BER brings together three core elements:

• Material characterisation: This establishes what the device is made from, how those materials are produced and what substances patients may be exposed to. It includes chemical composition, manufacturing residues, degradation pathways and surface properties. Without robust characterisation, biological risk cannot be meaningfully assessed.
• Biological test data: These data demonstrate how the material behaves in contact with cells, tissues and systems relevant to its intended use. Typical studies include cytotoxicity, irritation, sensitisation, systemic toxicity and (where appropriate) subacute, subchronic or implantation assessments.
• Toxicological interpretation: This step integrates chemical information with exposure estimates to determine whether any detected substances present a realistic risk. It is this risk-based analysis that allows a toxicologist to reach a defensible safety conclusion.

Why early BER planning prevents downstream delays

Waiting until late-stage development to consider the BER often forces developers into unplanned testing cycles or design revisions. Thinking about the BER early provides a clearer pathway through ISO 10993 requirements and avoids gaps that can halt progress.

Early planning ensures testing is targeted, not reactive

ISO 10993 does not prescribe a fixed checklist. Instead, tests are selected based on device contact type, duration and material composition. When these decisions are made early, the biological evaluation strategy aligns with the device architecture from the beginning, rather than being retrofitted once prototypes are complete.

It reduces the risk of discovering missing information too late

Many BER delays arise from incomplete material information like unknown additives, undocumented coatings, uncharacterised adhesives or untested suppliers. These gaps complicate the toxicological assessment and may require additional extractables, leachables or biocompatibility studies.

It shortens iteration cycles

In modern biosensor development, materials, surface chemistries and assay components evolve throughout R&D. With BER thinking integrated into early-stage design, each iteration can be evaluated for biological impact, allowing issues to be resolved before they become major regulatory obstacles.

The advantage of pre-validated materials in BER development

The choice of materials strongly influences the complexity of the BER. A substrate or sensing layer with no biological data requires new testing, which inevitably extends timelines and increases the probability of unexpected findings.

By contrast, materials that are already biologically characterised give manufacturers a major advantage.

This is where Gii, developed by iGii, is uniquely positioned. Although engineered for high electrical performance, Gii has also undergone an extensive biological evaluation programme, including:

• Cytotoxicity
• Irritation and sensitisation studies
• Systemic toxicity and subcutaneous implantation
• Extractables and leachables analysis
• A full toxicological risk assessment

Because the data already exists, they can be incorporated directly into a device’s BER. This does not replace device-level testing, but it substantially reduces the amount of foundational testing a manufacturer must commission themselves. It also provides toxicologists with reliable, standardised inputs for the chemical and biological risk assessment.

For biosensor teams under pressure to progress quickly (common in diagnostics), beginning with a material whose biological safety profile is already known removes a significant source of uncertainty from the development pathway.

Building a stronger biological safety strategy from the start

A device’s Biological Evaluation Report is the definitive demonstration of its biological safety, integrating material science, toxicology and empirical testing into a single structured justification. When manufacturers plan for the BER early, they avoid repeated testing, prevent last-minute surprises and enable smoother progression through ISO 10993 requirements.

Pre-validated materials such as Gii from iGii strengthen this process even further by providing high-quality biological safety data from the outset. By reducing the baseline testing burden, they allow development teams to focus on device performance while building their BER on a solid, scientifically robust foundation.

To explore how Gii can support BER planning and accelerate diagnostic development, download our guide below.