What does a wind turbine have in common with the KiCoPen insulin injector? They both generate electricity using electromagnetic induction.
Cambridge Consultants recently introduced the KiCoPen - an insulin injector that helps diabetics manage their insulin doses. The injector pen measures the exact amount of insulin that was injected and transmits that information to a smartphone app. The app will track dosage, ensuring that the user has maintained the correct insulin levels throughout the day. In addition to monitoring insulin injections, the app allows users to enter information about meals, carbohydrate intake, and blood glucose levels. The app will then calculate the correct insulin dose for the next injection.
Image courtesy of Cambridge Consultants
The KiCoPen includes a microchip that measures the amount of insulin that was injected and transmits that to a smartphone via the Bluetooth Smart (generically called “Bluetooth Low Energy”) protocol. Bluetooth Smart is a very low power version of Bluetooth that transmits short bursts of data using a fraction of the power of typical wireless transmissions. Bluetooth Smart can operate at powers as low as 10 mW with a minimum data packet of 64 bits. At one mbps, the transmission of data from the KiCoPen to the smartphone only takes a fraction of a millisecond.
Rather than powering the electronics with a battery, which would add cost and use toxic chemicals, engineers at Cambridge Consultants decided to harvest the energy of motion - in this case the motion of removing the cap from the injector pen - and convert that to electricity. A small permanent magnet on one piece moves near a coil of wire on the other piece, which generates electricity via electromagnetic induction. The cap removal generates well over 500 mJ of energy, which easily fits into a low-end supercapacitor. The supercap then becomes the “battery,” powering the microchip and the radio transmitter for the short data transmission, which requires about 300 - 500 mJ.
Energy harvesting is becoming popular in the medical electronics field, especially in implantable medical devices. Researchers at several universities have built piezoelectric devices that harvest the motion of a person’s heartbeat in order to power a pacemaker. These prototypes have produced up to 10 microwatts of power, almost an order of magnitude greater than the power needed by a pacemaker. Engineers at MIT are making a cochlear implant that harvests the body’s own electrochemical signals to power a small chip with a radio transmitter. This device would allow physicians to monitor a person’s hearing to look for potential causes of auditory afflictions. These are just a few of the many potential uses for energy harvesting in the biomedical field.
In the energy industry we’re seeing a convergence of efficiency and generation. On a large scale, this means energy efficient lighting and machinery coupled with renewable energy sources like solar and wind. Equally important but often overlooked, we have tiny devices with miniscule energy requirements that extract power from their surroundings. Whether you think big or think small, it’s a good time to be an engineer in the energy field!