Abstract: This disclosure provides a device and a method for combining a lumbar puncture needle and an ultrasonic density detection circuitry to provide an inexpensive and accurate lumbar puncture locator device. The disclosed device senses different tissue densities with different frequency tones and colored light indicators before needle insertion in the patient's lumbar vertebrae region. This invention allows a doctor, a nurse practitioner or a physician assistant to safely do a lumbar puncture in an office environment without the scheduling of the use of the radiology department. This device will allow a timelier diagnosis of infections (such as Lyme disease, bacterial and viral meningitis, herpes, West Nile virus, syphilis), multiple sclerosis, Alzheimer's dementia, tumors, idiopathic intracranial hypertension, subarachnoid hemorrhage, and others.