UFI UUB BioLogs
From 2000 feet below the Antarctic ice to 15,000 feet in the air, these tiny low-power physiological data loggers open new research frontiers
UFI initially developed the UUB BioLog for the Paul Ponganis Lab at Scripps Institution of Oceanography. Their ongoing studies of the diving physiology of emperor penguins had utilized our 3991 BioLogs for several years. These birds dive to depths of up to 1750 feet (534m) below the Antarctic sea ice, so the loggers require thick-walled pressure enclosures.
Even with cylindrical cross-sections, the enclosures for the 3991 logger boards created more drag on the penguins than desired. Could UFI develop a smaller logger package to fit into a pressure housing with an inside diameter of no more than about 0.5 inches (13mm), asked Scripps?
We replied in 2009 with the Universal Underwater Board (UUB). The "universal" part was intended to convey the message that this logger would support signal conditioners beyond just the the ECG functionality initially requested. And indeed, by adding a tiny 3-axis MEMS accelerometer chip to the 0.525" by 2.000" (13.3mm x 50.8mm) "core" board, we went a long way toward meeting the requirements of the five additional customers listed in the next section. Small added "daughterboards" piggy-backed onto the core boards met the remainder of their hardware requirements. Additions to the firmware for the logger microprocessors and to the PC host software did the rest.
Other examples of UUB applications
- UUB/4-EIAP for Weddell seals: Researchers at Texas A&M and UC Santa Cruz asked UFI to build them a system to log ECG and IBI (interbeat interval), 3-axis acceleration and seawater pressure. This system was deployed in 2009 on ambulatory Weddell seals near McMurdo Station, Antarctica. The seals traveled several days between instrument deployment at holes in the sea ice and later recovery there. Since Weddell seals dive to depths of 600 meters (2000 feet) below the ice, strong pressure enclosures were essential.
- UUB/3-EIA for dolphins: A joint US Navy/UC Santa Cruz research team requested a data logger for use in the Navy's Marine Mammal Program. In June 2009, UFI delivered a logging system to allow them to record ECG and IBI data from ambulatory dolphins swimming at relatively shallow depth.
- UUB/3-EA for condors: The California Condor Ecology & Management unit of San Diego Zoo's Institute for Conservation Research asked whether UFI could construct an ECG and two-axis acceleration logger to soar on the backs of the free-ranging birds, potentially to 15,000 feet (4.6 km). A first system was delivered in December 2009; in May 2010, UFI delivered a much-improved system.
In the newer system, the accelerometer helps conserve memory and battery power: when measurements indicate the condor has roosted for the night, recording pauses. Data logging resumes only when accelerometer activity again shows flight behavior. - UUB/3-EPT for geese: A research associate at the University of British Columbia asked UFI to design a logger to measure partial pressure of oxygen (PO2), as well as ECG and acceleration. UFI delivered the loggers, which will be deployed on geese, in mid-2010. First loggers will be tested in a wind tunnel; if all goes well, later measurements may include free-ranging birds.
- UUB/6-EAPD for elephant seals: Research personnel at Woods Hole Oceanographic Institution asked UFI to propose a sophisticated logger to measure ECG, two-axis acceleration, sea-water pressure and oxygen saturation. In a first phase, the logger will be deployed to study the diving response of elephant seals; the recorder later may be deployed on even larger marine mammals.
Features common to all UUBs
- A wide range of signal conditioners are available/li>
- Available sensor inputs include ECG/HR/IBI, EOG, EMG, EGG, EEG, respiration, PPG/PTT, pressure, temperature and more
- UFI proprietary front-ends (input sensors) include Skin Conductance Level (SCL) and Impedance Respiration
- Each input signal conditioner is designed to your specifications of gain, frequency response, sample rate, etc.
- Fetrodes™ can be used on all bioelectric channels to reduce input noise at the source
- Battery operation (usually long-lasting 3.6V lithium cell) gives inherent subject isolation
- removable microSD cards give flexible amounts of data storage
- Data are downloaded through UFI interface boxes, including the Model 3991BIB
Typical underwater deployment in customer-supplied housing
This data logger is the UUB/4-EIAP model, configured here to measure ECG and IBI (interbeat interval), 3-axis acceleration and seawater pressure up to 2000 feet (600m) below sea level. The pressure transducer screws into the black housing end cap shown at left; the ECG electrode cable attaches to the underwater connector on the end cap at right.
The single 3.6V AA lithium cell at left powers all channels for over 56 hours of recording time using 50 Hz ECG sampling. Time is not limited by the battery -- estimated to yield 600 hours of data collection -- but simply by the memory configuration used here.
Assembly of the logger electronics package into the housing follows a prescribed sequence of steps in order to use the smallest possible underwater housing. The smaller and lighter the logger assembly, the less likely it is to alter normal Weddell seal diving behavior and the less likely it is to be knocked off during deployment.
The assembled size of the logger with housing is just over 6 inches (150mm) long by 1 inch (25mm) in diameter. It could be even smaller if deployed to lower depths and a thinner housing wall were possible. Deployment on birds requires only a weather-resistant housing: our condor logger weighs just 1.4 ounces (40 grams) including battery and case.
UUB core-board specifications
- ECG sampling rates: 25 Hz, 50 Hz or 100 Hz, selectable
- ECG full-scale voltage at input: +/- 2.5 millivolts
- ECG gain: 1,000
- ECG sample resolution: 12 bits (about 0.6 microvolts at input)
- IBI (optional) sample rate: 1000 Hz
- Accelerometer sample recording rate: 20 Hz - all three axes
- Accelerometer range: +/- 2.0g (+/- 19.6 m/sec2) - all three axes
- Accelerometer sensitivity: 0.018g (+/- 0.18 m/sec2) - all three axes
- Additional input channels: provision for three additional A-to-D inputs plus three additional digital I/O control signals
- Logger memory: removable microSD card
- Recording duration: as needed (as of April 2010, longest configured duration for 50 Hz ECG plus two acceleration channels was 162 hours (6.8 days)
- Assembled logger board dimensions: 2.00" long x 0.57" wide (overall) x 0.30" thick (51mm x 14.5mm x 7.6mm) - battery is external to board
- Assembled logger board weight: about 0.3 ounce (9g)
- Power supply: cylindrical 3.6V primary lithium cells recommended
- Sizes of recommended batteries: all are 0.57" (14.5mm) diameter; 1/2AA is 0.99" (25.1mm) long; 2/3AA is 1.32" (33.5mm) long; AA is 1.99" (50.5mm) long
- Weights of recommended batteries: 1/2AA, 0.32 ounce (9g); 2/3AA, 0.44 ounce (12.5g); AA - 0.62 ounce (17.4g)
- PC interfacing: Model 3991BIB interface box
- PC software: UFI BioLog DPS, written to user requirements, for logger initialization and data monitoring, download and display
- Pricing: Call, fax or email us with your requirements. We'll be happy to respond with a prompt quote.