Show HN: NFC Energy-Harvesting PCB Business Card with an MCU
wilsonharper.net
wilsonharper.net
I wonder if it can be applied to robo-couriers and drone drop-offs. One of those comes to your door, you get your stuff, and you pass something that is powered-up over its sensor and it drives off. It's the equivalent of signing-off on a delivery. The sensor obtains and stores information about you as well.
Maybe I've got it wrong and the recipient needs the sensor and the driver has the powered device that only switches on when it is ready to do the drop off.
With this card, what are the information transfer and storage scenarios? Would be great to see a table. Can the two parties both exchange and store information with minimal power? A card with a little battery and power-on button? Card can have some type of port? Can it be be used as a crypto wallet with a kill switch in the event of a robbery or home invasion?
I think this is important in Hub-and-Spoke communities (previous comment) where population densities decrease but there'll still have to be a lot of exchange going on. Offline-based interactions are a good idea too - keep the airwaves clean.
Another interesting use case would be using the card as part of a crypto escrow.
The problems being solved here are:
- walking around with a device that can access a large wallet that could be accessed under duress or coercion
- Key Pairs are hard to remember and type
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- pre-pay an escrow online with $100
- have a payment card in your pocket
- meet person with another card
- set a payment amount
- touch cards
- escrow unlocks the amount as soon as either card pushes the update online - which if online could be immediately
- card confirms the transaction??
- can also delay the transaction, and if both cards are lost in the meantime, the transaction doesn't go through
- can also specify the payment amount as "set later"
- receiver can also request an amount
- escrow can be funded after the meeting
- good for 1:many payments too, eg splitting a bill
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cards could also be Key Pair generators, for transferring public keys to other cards, with the exchange recorded for later use. No escrow required. A lot of benefits over handing out printed QR codes of addresses.
The card can work with Lay-buy/lay-by:
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You go into a store, pick something out. Get a crypto address for it and the amount required with your special card. They set the thing aside. You leave and return to the store when the transaction has gone through and get your stuff.
You don't pay immediately because you don't want to be walking around with a crypto wallet or a crypto debit card. The merchant doesn't want to pay fees either when dealing with an intermediary. There's no fiat conversion either, at least not as a given.
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Gemini says this:
"If you want to do this today, ask the merchant to print or email you a dynamic checkout invoice/QR code so you can complete the transfer on your own device later."
But how widespread is that?
"It is virtually non-existent at retail scale. While the underlying technology exists, you will practically never encounter this specific workflow in the wild."
https://share.gemini.google/ZBHVZo47ZSn1
The "special card" is an evolution of that use-case and organizes it better. You can leave home without thinking about dollars, ready to pay with crypto and not worry about being robbed. No worrying about stockpiling a bunch of receipts either. It's just a 2-step buying process, that's the downside. The shop also has to hope you end up paying once they set it aside. Maybe they'll need a deposit. They can offer deliveries?
Another idea is to pay online and collect it later. Use the card to authenticate yourself when you collect. That would need some decent tech backing it. Make it non-committal where if you don't collect within a certain time frame, you get your money back but lose a penalty chunk.
Isn't this what smart contracts are designed for - crypto transactions tied to real world events? The "special card" provides those events.
[ conversation continued via link above ]
In a drone or robo delivery case, there is already a massive power storage budget available, so I don’t see the particular advantage of this hack being relevant.
Regarding robotaxis:
"The side of the vehicle features a rugged touch screen. You receive a 4-digit PIN via text or app notification, walk up to the vehicle, and type that code into the car's screen to open the specific compartment holding your order."
https://share.gemini.google/wzuailgn9yih
You could roll up with your "unpowered keypad" to the taxi and key in a PIN via that. Saves the car from installing one, and there'd be an extra layer of security whereby your card could be coupled with the drop-off. It makes sense when you don't have or want a smartphone. (see below)
"External touchscreens mounted on autonomous delivery vehicles face several severe real-world challenges, making them one of the highest-maintenance hardware components on the vehicle... By shifting authentication back to the customer's phone, operators eliminate the weatherproofing and vandalism headaches of external screens while speeding up the drop-off process."
Gemini says you can power a piezo buzzer (causing a small bump on a PCB) w/ NFC (just enough power to drive it) to play the modem dialup handshake audio.
If I were to purchase, say, 150, the marginal cost would go down greatly, and $8 is low enough that I'm still happy to give them to folks at career fairs.
Can somebody explain how this actually works (Physics + Technology) with pointers to further resources? I have been meaning to look deeper into "Energy Harvesting Systems" and running a MCU using that but never really sat down to research it properly. Some links;
University of Washington - WISP (Wireless Identification and Sensing Platform) - https://sensor.cs.washington.edu/research/wisp_1
Perpetually Powered Energy Harvesting Systems Using the MSP430 MCU - https://www.ti.com/video/3870842958001