Blockchain Integration for Healthcare Records

I run an electronic health-record platform and I am ready to weave blockchain into it so every update, hand-off, and patient consent is cryptographically sealed and instantly auditable. Development is the focus—I already have the front-end, databases, and HIPAA policies in place; what I need now is the chain layer, the smart-contract logic, and the glue code that lets the current system talk to the ledger in real time.

Here is what the engagement will look like:
• Architecture & chain selection: help me decide between a permissioned network such as Hyperledger Fabric or a public chain with private side-channels (I’m open, as long as it meets compliance and performance targets).
• Smart-contract package: patient-record hash storage, role-based access control, and a consent-revocation flow.
• Integration middleware: REST/GraphQL endpoints or direct SDK calls that let our .NET back-end log and retrieve blockchain events without slowing normal EHR operations.
• Testing & hand-over: unit tests, a small sandbox network, and clear deployment scripts so my DevOps team can push to staging and production.

Acceptance criteria
1. A record created or modified in the existing EHR surfaces on the chain within two seconds.
2. Access-control checks are enforced exclusively on-chain and pass all provided test cases.
3. Full documentation (setup, APIs, contract ABIs) is delivered and reviewed with my tech lead.

If you have hands-on experience moving sensitive healthcare data onto a blockchain, I would love to see how you would tackle this.