A strain gauge and method of making same for use in certain medical applications, such as sensing the occurrence of an apnea event. The device is also applicable to monitoring mechanical motion associated with other medical conditions. The strain gauge actually measures the change in direct current resistance produced by stretching and compression of a number of carbon deposits coupled in series on a longitudinally extendible substrate. This extendibility is produced by suitably die cutting a flexible but inherently inelastic insulative substrate. The easily produced device may be used externally or encapsulated for implantation.