A hardware wallet that stores and transfers cash digitally


Phygital Cash is a secure and portable hardware wallet that stores and transfers digital cash in an offline setting. The hardware wallet is designed to be used for daily, small expenditures. At the same time, it aims at addressing the underbanked population, by giving them access to digital payment methods irrespective of a bank account.

The project is based on an industry challenge given by Tata Consultancy Services at Cornell Tech.

Project Type: Group project

Team: 2 Electronic computer engineers, 1 Business associate, 1 UX Designer

Role: Research, Concept, Visual Design, Prototype, User Testing

Duration: 3 months

Tools: Figma, Xcode, Swift

The Process

The process for this project was defined according to the project scope, needs and challenges.

Phygital Cash
Phygital Cash


How might we create a 'Phygital Currency' that includes the capabilities of both physical and digital currencies.


As a solution, we built a dedicated hardware using the offline transfer protocol that incorporated the proximity technology of an NFC tag. At the same time, we built a simple UI that's secured by biometric authentication.

Phygital Cash


We started working on the solution by first understanding the current adoption and problems with cash and digital payment methods.

Current Concerns with Cash:

  • For businesses and individuals, cash doesn't not provide enough security

  • Cash is not digitally compatible

  • Cash payments are clunky

  • Governments and banks have to deal with counterfeit cash problems

  • Cash is costly for banks and a burden for governments combatting the black economy

Steps to use digital payment methods
Phygital Cash
Phygital Cash

Current Concerns with Digital Payment Methods:

Digital Payment methods are on a rise, but there are too many players and steps involved. Currently, these methods are only available for the banked population. According to Global Findex Database, 1.7 billion adults worldwide are underbanked. There is no current digital solution that serves them.

Phygital Cash



Completing transactions on the phygital device can be more convenient than existing digital solutions and close to the convenience of cash.


  • We purchased and tested cheap, programmable NFC tags to 'hold' digital cash offline. These were placed on 3d printed plastic 'coins' to test.

  • We also built a working, prototype app to load and unload 'cash' from the NFC tags. The NFC tags store theoretical  'value' on an offline network.

Experimentation Plan

We want to test the convenience of our offline, hardware-based approach versus cash and existing digital payment solutions. To test convenience, we will equate convenience to time. We are assuming that if the user saves time, then our approach is convenient.

Phygital Cash

Treatment 1

Test loading 'cash' ($5) onto the Phygital coin from the mobile app two times in a row.

Treatment 2

Test unloading 'cash' ($5) from the device two times in a row to buy a pen from another person. The seller of the pen will be instructed not to hand over the pen until they see the money in their account. This simulates a p2p payment or in-person purchase.

Phygital Cash


Sample Size: 9
Interviewees: Venmo and Non Venmo Users
Duration: 5 mins


  • Our prototype is faster than Venmo and slower than Cash

  • Our experiments yielded valuable qualitative behavioral data in addition to quantitative data

  • Older users were more wary of their money 

  • Reliability is key - it’s hard to beat the reliability of physical cash

Phygital Cash


We consider our hypothesis validated, as phygital cash turned out to be faster than Venmo for payments and close to physical cash. However, our product does not beat physical cash for its convenient and prompt peer-to-peer transactions. Our next step would be to bridge this gap by beating the next best digital payment method. Since Phygital Cash will add offline support as per our prototype, we will consider this a valid breach into the realm of making 'Phygital' currency and can continue with other experiments.