Because spinal injury, the patient's voiding dysfunction, usually have to urinate in the body to retain the catheter. However, this method often causes urinary tract infections and bladder stones. If the involved kidney, and even endanger the patient's life. Electronic bladder stimulation is to solve the lower motor neurons in patients with poor voiding function and design. The stimulator includes two parts, the transmitter and receiver, the block diagram shown in Figure. Transmitter placed outside the body, it launched the 1MHz carrier frequency of the pulse modulation signal. The receiver is a passive network, with all the medical silicone rubber seal, permanently buried in the body. The output wires and electrodes connected with the bladder wall. When the transmitter work, the output of the receiver low-frequency pulse to stimulate the detrusor bladder wall, so that contraction, so as to achieve the purpose of urine excretion. After several animal experiments show good results.
Electronic bladder stimulation energy is actually a radio transmitter. Its transmitter requirements are:enough working distance (greater than 2.5cm); have enough power output. Due to weight, size limits, and because the receiver is a passive network, so the stimulator and the general requirements of a radio transmitter and receiver has its different specificity.
Figure (a) circuit diagram for the stimulator (transmitter section). TV1 and TV2 in which the composition multivibrator, the pulse frequency of 60Hz, pulse width of 1ms. VT3 as the sine wave oscillator frequency of 1MHz. Low-frequency pulse multivibrator VD1 of 1MHz sine wave by the pulse modulation. VT1 ~ VT3 are 3DG6 tube; VT4 by 3DG12 tube; VT5 by 3DD2-tube, VT6 with 3DD15 tube. VD1 by 2AP9 tube; VD2, VD3 are used 2CK10 tube.

Modulated signal through VT4 and VT6 VT5 driven power amplification and amplification, was launched last out. In the receiver section shown in Figure (b), where, L and the resonant circuit composed of C1 *, VD1 * ~ VD4 * for the bridge detector, R1 *, R2 *, C2 *, C3 * composition blocking network. Transmitter in the C13, L2 and receiver in the L, C1 * composed of two resonant circuits, the resonant frequency was 1MHz.
In Figure (a), the coil L1 with F0.1mm enameled in F10mm, length 15mm pipe insulation around the 200 turn, are around 5 minutes. L2 12 turns enameled wire with F1.5mm, diameter 42mm. L 9 turns with 1.5mm enameled wire around the outside diameter of 47mm. High-frequency transformer T1 and T2 respectively F0.2mm 40 turns enameled wire around the primary, F0.6mm 10 turns enameled wire around the secondary; ring is F13 × F8 × 8 (NX-100). CD1 and CD2 for the two 24V nickel-cadmium batteries.
Figure (a) in the R11 and C17 for the storage network. The gap in working hours amplifier, power supply through resistor R11 to charge capacitor C17. When the voltage on the capacitor up to the supply voltage, the amplifier stage began to short-term work. Capacitor discharge, power amplifier class power consumption of the burden from the capacitor. The stimulator take R11 to 250O, C17 take 2000µF. Therefore, the application of energy storage networks, reducing energy consumption of the power amplifier.
The role of electronic bladder stimulator object is the bladder, the receiver the received signal current through the detector from the lead, the electrode acts on the bladder wall detrusor, the bladder is equivalent to the receiver load. The stimulation of the transmitter, receiver and the connection between the bladder as shown in Figure.

When the bladder is low-frequency electric pulse, the bladder is mainly characterized as a pure resistance RH. RH depends entirely on the size of the bladder wall and the electrolyte concentration, the body's own resistance. A large number of test shows that: not only the equivalent resistance of the bladder varies, but may also be due to different electrode position have a greater change in the electrode should be buried in the top of the bladder, the bipolar spacing of 2mm, causing a large area of bladder contraction. If the triangle is placed in the premature contraction of the bladder neck caused or was gourd-like contraction, and can not urinate. Change in equivalent resistance range up to 50 ~ 200O.
Human bladder is a low impedance load, to build up enough voltage on it must take into account the transmitter, receiver and impedance matching between the body and power transmission. Experiments show that when the work a maximum of the pulse is 20 ~ 30V maximum instantaneous power when the PH is 8 ~ 18W in order to make the bladder wall detrusor contraction.
Because the bladder wall and the contact resistance between the electrode, its value is roughly 2 ~ 5O, so when the current through the contact surface between them must generate heat. If the heat accumulated to a certain extent, there will be the contact surface of the muscle burn, or even tissue necrosis. From the experimental results, due to the bladder wall, 0.5 ~ 0.1W/cm power density is a critical area. In order to limit the power density in the security area, should be 4 pairs of electrodes, diameter 6mm, buried in the bladder muscle layer and serous layer, which provides a large area of low resistance stimulation of the facial. Therefore, in the experiment did not find significant burns animal bladder phenomenon.
Physiological role of human urine by two nerve center of the control. The nerve center of the more important in the lumbar spine among 2,3,4; another minor nerve center located in the brain. Although some patients have been on the motor nerve damage, and the bladder has not been damaged spinal center after injury a few weeks or months can create "automatic reflex bladder" and urine, so this device is only applicable under the motor neurons of the burn patients.