People with diabetes must regularly check their blood sugar levels and manually inject insulin or use other treatments. To automate the process, Haifeng Ye of East China Normal University in Shanghai and his colleagues engineered human cells to express insulin when exposed to far-red light. The team then implanted the cells into mice, along with specially designed light-emitting diodes (LEDs). A smartphone app communicated wirelessly with a home server that controlled the LEDs. When the researchers switched on the lights, the cells produced insulin.
The authors adapted this system to regulate insulin in mice in response to blood sugar levels. A glucometer measured glucose in blood taken from the animals and sent a wireless signal to the smartphone. The system rapidly returned insulin to normal levels.