Micro-Payments and Secure Audit-Trails

At the start of the PoC, we hand-picked certain data produced from the real manufactured components for storing it as a digital twin that resides in the Tangle network. (see Status Report 01). As the project progressed, further concepts such as Micro-Payments and Secure Audit-Trail were also tested (see Status Report 04). Those reports represent a supply chain from manufacturer to end-user or customer, as shown in Figure 1.

Figure 1: Micro-Payments & Secure Audit-Trail. Image: © WZL | Daniel Trauth & Semjon Becker


  • The supply chain begins with a machine tool manufacturer. In this example, we use fine-blanking machine as our press manufacture, but this can also be a milling machine or plastic injection moulding machine manufacturer.
  • These machines are used by one or more producers to manufacture individual components.
  • Furthermore, we assumed that an original equipment manufacturer (OEM) assembles the individual components into a finished assembly, a product, and does not sell them directly to the customer.
  • The trade is done by the retailers.
  • The end of the supply chain is the end customer who uses the assembly or product.

Definition of Micro-Payments

The term Micro-Payment refers to a payment method for small sums of money, which are primarily known when digital goods are purchased. Depending on the region and culture, amounts between $0.01 to $5 can be referred to as a Micro-Payment. Based on recent developments, however, Micro-Payments are particularly useful when it comes to amounts that cannot be economically transferred with the conventional means of payment. This is due to the fact that the transaction fees are higher than the value of the transaction itself. Since Distributed Ledger Technologies (in this instance IOTA) can be used to send fee-less transactions, amounts of less than $0.01 are now economically feasible. In a supply chain case, Micro-Payments must be at the beginning of a value chain, since the added value there is lower in the first step compared to the entire assembly. Irrespective of this, Micro-Payments require a rethinking of production. The conversion of a physical payment into a digital one for the sole purpose of modernising value creation will not suffice, see Chapter Pay Per Click and Subscription Models in a Manufacturing Economy.

Definition of a Secure Audit-Trail

The increasing demand from industry and trade for more transparency across the entire supply chain, combined with the clear clarification of responsibilities for interventions and changes, is leading the automotive industry in particular to monitor interventions closely. Unauthorised interventions and changes in highly sensitive goods and substances can sometimes have extreme effects on the condition and quality of the product. In order to minimise and detect quality losses, intervention protocols recorded in the audit trail for downstream stages in the supply chain can be requested and viewed at any time. Manipulations will be next to impossible due to the qualification prior to commissioning of the systems. Accordingly, an audit trail is a quality assurance tool and serves to control and record changes made in processes. In contrast to known monitoring systems, which continuously monitor certain processes, audit trails focus on monitoring changes and deletions made across the entire supply chain. Thus, interventions in processes for downstream levels in supply and value chains are understandable, controllable and fully visible. Based on Figure 1, a Secure Audit-Trail extends from production to the end customer and can be expanded as necessary, e.g. by extracting raw materials using environmentally friendly methods.