TY - GEN
T1 - Rectangular cymbal arrays for ultrasonic transdermal insulin delivery
AU - Luis, Joseph
AU - Park, Eun Joo
AU - Meyer, Richard J.
AU - Smith, Nadine Barrie
PY - 2007
Y1 - 2007
N2 - Studies have shown that ultrasound mediated transdermal drug delivery offers a promising potential for needle-less insulin delivery for diabetes treatment. Arrays of cymbal transducers have been shown to be effective in delivering therapeutic levels of insulin to decrease hyperglycemic glucose levels in rats, rabbits and pigs. To improve delivery efficiency of the cymbal arrays, an increase in the spatial intensity field without increasing the size the device or Isptp was desired. A 3 × 1 rectangular cymbal array was designed for this purpose. Rectangular cymbals maximized packing density and allowed the flexural cap resonance and the ceramic length mode resonance frequencies to be designed closer in frequency. Bringing the cap and ceramic resonances closer together increased the transmitting power and improved the electrical efficiency. By using higher order modes excited in the cap while operating at the first ceramic resonance frequency, the intensity spatial area was increased compared to the circular array. With a similar intensity (I sptp ≈ 50 mW/cm2), our goal was to determine if the 3 × 1 rectangular cymbal array could perform significantly better than the 3 × 3 circular array for blood glucose reduction in hyperglycemic rabbits. Nine New Zealand White rabbit (≈ 4.0 kg) experiments were performed in three groups: control (n = 3) and ultrasound exposure with the 3 × 3 circular cymbal array (n = 3) or 3 × 1 rectangular cymbal array (n = 3). The rabbits were anesthetized and their thigh area was shaved for the exposure. A water tight reservoir which held the insulin was fastened between the rabbit's thigh and the ultrasound arrays. At the beginning of the experiment and every 15 minutes for 90 minutes, 0.3 ml of blood was collected from the ear vein to determine the glucose level (mg/dl) using a glucose monitoring system. For comparison between individual rabbits, the change in the blood glucose level was normalized to their initial baseline value. For the control group, the glucose level increased (i.e. more hyperglycemic) to maximum of +80.0 ± 28.8 mg/dl over the 90 minute experiment. Using the 3 × 3 circular array, the blood glucose level decreased to -146.7 ± 17.8 mg/dl at 90 minutes. However, in comparison using the 3 × 1 rectangular cymbal array, the blood glucose decreased faster and to level of -200.8 ±5.9 mg/dl after 90 minutes for 25% improvement. These results indicated the potential of the rectangular cymbal array as an advanced device for portable drug delivery by decreasing the power consumed and increasing the insulin delivery rate.
AB - Studies have shown that ultrasound mediated transdermal drug delivery offers a promising potential for needle-less insulin delivery for diabetes treatment. Arrays of cymbal transducers have been shown to be effective in delivering therapeutic levels of insulin to decrease hyperglycemic glucose levels in rats, rabbits and pigs. To improve delivery efficiency of the cymbal arrays, an increase in the spatial intensity field without increasing the size the device or Isptp was desired. A 3 × 1 rectangular cymbal array was designed for this purpose. Rectangular cymbals maximized packing density and allowed the flexural cap resonance and the ceramic length mode resonance frequencies to be designed closer in frequency. Bringing the cap and ceramic resonances closer together increased the transmitting power and improved the electrical efficiency. By using higher order modes excited in the cap while operating at the first ceramic resonance frequency, the intensity spatial area was increased compared to the circular array. With a similar intensity (I sptp ≈ 50 mW/cm2), our goal was to determine if the 3 × 1 rectangular cymbal array could perform significantly better than the 3 × 3 circular array for blood glucose reduction in hyperglycemic rabbits. Nine New Zealand White rabbit (≈ 4.0 kg) experiments were performed in three groups: control (n = 3) and ultrasound exposure with the 3 × 3 circular cymbal array (n = 3) or 3 × 1 rectangular cymbal array (n = 3). The rabbits were anesthetized and their thigh area was shaved for the exposure. A water tight reservoir which held the insulin was fastened between the rabbit's thigh and the ultrasound arrays. At the beginning of the experiment and every 15 minutes for 90 minutes, 0.3 ml of blood was collected from the ear vein to determine the glucose level (mg/dl) using a glucose monitoring system. For comparison between individual rabbits, the change in the blood glucose level was normalized to their initial baseline value. For the control group, the glucose level increased (i.e. more hyperglycemic) to maximum of +80.0 ± 28.8 mg/dl over the 90 minute experiment. Using the 3 × 3 circular array, the blood glucose level decreased to -146.7 ± 17.8 mg/dl at 90 minutes. However, in comparison using the 3 × 1 rectangular cymbal array, the blood glucose decreased faster and to level of -200.8 ±5.9 mg/dl after 90 minutes for 25% improvement. These results indicated the potential of the rectangular cymbal array as an advanced device for portable drug delivery by decreasing the power consumed and increasing the insulin delivery rate.
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U2 - 10.1109/ULTSYM.2007.215
DO - 10.1109/ULTSYM.2007.215
M3 - Conference contribution
AN - SCOPUS:48149088972
SN - 1424413834
SN - 9781424413836
T3 - Proceedings - IEEE Ultrasonics Symposium
SP - 840
EP - 843
BT - 2007 IEEE Ultrasonics Symposium Proceedings, IUS
T2 - 2007 IEEE Ultrasonics Symposium, IUS
Y2 - 28 October 2007 through 31 October 2007
ER -