Soulbound token applications. A case study in the health sector

This paper focuses on the concept of blockchain soulbound tokens, their potential applications, and their implementation in Ethereum-based blockchains. Soulbound tokens add an important piece to blockchain technology, as they could be the key to building Web3 and a trustworthy decentralized society. Issued and strictly linked to an account, representing the soul of a user, the soulbound token makes it possible to represent a property that only the user can have and that cannot be transferred, but only removed, which enhances security. To evaluate their impact on blockchain development, we first examine the concept of soulbound tokens, their potential applications, and their effective adoption. The application sectors include the creation of digital identity certificates, ownership certificates, reputational certificates, governance, and the healthcare sector. We then report and describe relevant blockchain token standards, including soulbound token standards, provided in the form of Ethereum Improvement Proposals. Finally, to study the efficacy of the implementation of soulbound tokens, we propose a case study that includes the design and development of a decentralized vaccine certification prototype based on soulbound tokens. In our system, the vaccination data produced by the health authority is fully decentralized and implemented as the issuance of soulbound tokens for the benefit of a citizen's soul account. As a result, the citizen is the only owner of the vaccination data.