US retail giant Walmart has applied for a patent for a smart shopping trolley that can track a shopper's heart rate, temperature, grip and walking speed.
Such a system would provide valuable information about how shoppers respond to different stores, it said.
The patent, submitted in February, would see trolleys fitted with sensors which in turn send data over the internet to Walmart's servers.
Walmart said it would not collect any personally identifiable data.
The patent, published in August, is titled "System and Method for a Biometric Feedback Cart Handle".
Walmart said that the internet-connected trolleys would be useful "for alerting store associates that a customer may need assistance".
It described how the trolley would start collecting data when a customer starts using it and stop when it is no longer in use.
Technology blog CBInsights commented on the patent: "If biometric indicators show signs of emergency, the program may also issue a broadcast throughout the store to call associates' attention to the situation, and could potentially initiate a call for emergency medical help as well."