As wireless bio-medical long term monitoring moves towards personal monitoring it demands very high input impedance systems capable to extend the reading of bio-signal during the daily activities offering a kind of "stress free", convenient connection, with no need for skin preparation. In particular we highlight the development and broad applications of our own circuits for wearable bio-potential sensor systems enabled by the use of an FET based amplifier circuit with sufficiently high impedance to allow the use of passive dry electrodes which overcome the significant barrier of gel based contacts. In this paper we present the ability of dry electrodes in long term monitoring of ECG, EEG and fetal ECG.

BackgroundPregnancy testing in cattle is commonly invasive requiring manual rectal palpation of the reproductive tract that presents risks to the operator and pregnancy. Alternative non-invasive tests have been developed but have not gained popularity due to poor specificity, sensitivity and the inconvenience of sample handling. Our aim is to present the pilot study and proof of concept of a new non invasive technique to sense the presence and age (limited to the closest trimester of pregnancy) of the foetus by recording the electrical and audio signals produced by the foetus heartbeat using an array of specialized sensors embedded in a stand alone handheld prototype device. The device was applied to the right flank (approximately at the intercept of a horizontal line drawn through the right mid femur region of the cow and a vertical line drawn anywhere between lumbar vertebrae 3 to 5) of more than 2000 cattle from 13 different farms, including pregnant and not pregnant, a diversity of breeds, and both dairy and beef herds. Pregnancy status response is given “on the spot” from an optimized machine learning algorithm running on the device within seconds after data collection.ResultsUsing combined electrical and audio foetal signals we detected pregnancy with a sensitivity of 87.6% and a specificity of 74.6% for all recorded data. Those values increase to 91% and 81% respectively by removing files with excessive noise (19%).Foetus ageing was achieved by comparing the detected foetus heart-rate with published tables. However, given the challenging farm environment of a restless cow, correct foetus ageing was achieved for only 21% of the correctly diagnosed pregnant cows.ConclusionsIn conclusion we have found that combining ECG and PCG measurements on the right flank of cattle provides a reliable and rapid method of pregnancy testing. The device has potential to be applied by unskilled operators. This will generate more efficient and productive management of farms. There is potential for the device to be applied to large endangered quadrupeds in captive breeding programs where early, safe and reliable pregnancy diagnosis can be imperative but currently difficult to achieve.

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Context. Businesses within the Australian cattle industries and associated research and advisory agencies require accurate data on production and performance of the national herd. Currently, these are derived from survey and statistical data; the latter is expected to be accurate, but the former needs to be tested in view of information suggesting significant under-reporting.Aims. The research aimed to define the structure, performance and liveweight production of the Australian cattle herd and describe changes in reproduction, growth and survival over the past 40-50 years.Methods. Interactive static herd modelling of beef and dairy herds was reconciled each year from 1976 to 2018, using slaughter and live export statistics and surveyed dairy cow numbers. A principle applied was that model performance should dictate input variables, moderating information derived from publications and professional opinion.Key results. The Australian cattle herd fluctuated in size till the mid-1980s from when it settled into a range of 30-40 million beef cattle (12-16 Mt), exceeding survey data by 56-75%. The dairy herd remained at~10% of the beef herd. Despite consistent herd size, productivity of the cattle herd increased from~2.5 to 4.5 Mt of liveweight annually over 35 years. Half of this change was due to reductions in mortality, though~1 million post-weaning-age cattle still die annually, in addition to >0.5 million calves from birth to weaning. Approximately a quarter each of the change was due to increased reproductive output and to steer growth. Liveweight production per beef animal increased from 70-75 kg/ year to 130-135 kg/year, while liveweight production ratio increased by 0.08 and 0.12 kg/kg of cattle in male and female beef cattle respectively, to reach 0.31 kg/kg of cattle.Conclusions. The main conclusion is the size, performance, production and productivity of the Australian cattle herd are quite different from that determined from surveys. Also, there is an on-going opportunity to derive benefit from improving cattle survival, reproduction and growth and from improving the feed base.Implications. This research may have large impact on priorities for Australian beef business and associated environmental management. It is recommended that surveys be used to derive relative values to use in combination with absolute statistical data to derive accurate herd measures.