Nothing fishy about portable scope apps

Researchers get a charge out of measuring eels with battery powered oscilloscopes.

Crampton and the BBC film crew look for electric eels in the Amazon. Image courtesy of Will Crampton

Next time you find yourself swimming around with electric eels, try grabbing one and then put the leads of a battery powered oscilloscope on its head and tail. According to University of Central Florida zoology professor Will Crampton, you’ll probably measure a voltage in the700-V range.

Crampton and his associates went to the rivers of the Amazon to check out eel voltages. “Capturing eels out of the wild takes a lot of patience,” says Crampton. His technique for finding test subjects consisted of either setting up un-baited traps that eels can’t easily get out of, or using baited hooks to lure the eels from hiding.

Crampton’s procedure for measuring the electricity in eels employs a portable oscilloscope (a hand-held Fluke 124B industrial ScopeMeter), a small trench, and a tarp. Once caught, the eels go into paddling pools to reduce the shock of captivation and help them settle down. Crampton then prepares the area for the measurements by digging an eel-sized trench in the ground that will help hold the eel securely in place. The trench is covered with a non-conductive plastic tarpaulin, necessary to isolate the eel and remove it from the load of the water to get an accurate reading.

The portable oscilloscope is set up for a differential voltage measurement. To get an electrical reaction out of the eel, Crampton holds one probe tightly on the tail and uses the other probe to prod the eel’s snout. With the meter set to triggered acquisition, the oscilloscope captures short pulses of electricity. Once the measurements are taken, Crampton uses the cursor function to measure the difference between the highest and lowest point of the pulses.

The new measurement technique developed by Crampton earned him a Guinness World Record for most electric animal; an electric eel measuring in at 860 V took the title. Previously, the highest voltage output measured was also from an electric eel but was closer to 650 V. Crampton used the same measurement method to break the world record as he did on a recent trip to Guyana.

Eel measurement data using a Fluke 124B Industrial Portable Oscilloscope. Image courtesy of Will Crampton

Crampton went back to the Amazon to try and break the world record again as part of filming an episode for a BBC show called Animal Impossible. Crampton and a video crew spent nine days in Guyana looking for and measuring the voltage of electric eels. They recorded measurements from two different electric eels— both were the E. Electricus species—measuring in at 1.30 and 1.35-m long. Voltage readings for both eels were above 700 V, which would have broken the previous record.

Interest in the electrogenic capacities of electric eels (and their cousins the torpedo/ electric rays) dates back to 1800 when they became models for the first batteries. Understanding more about these animals, including voltage measurements, has helped with medical research leading to amazing discoveries. There are already electric eel organs being used as models for synthetic bio-batteries and future medical applications include powering medical devices like pacemakers or developing “biotechnology to allow human cells to generate sizable electric fields, external electric fields, which could be used as everlasting batteries,” according to Crampton.

References: Fluke hand-held 124B Industrial ScopeMeter, https:// www.fluke-direct.com/product/ fluke-124b-oscilloscopedual-input-multimeter-andrecorder-with-cursors