I hesitate to say so, but the greatest innovation in my main field of work, viz. the pathophysiology of blood platelets, is apparently the method for quantifying platelet aggregation and its inhibition known as optical aggregometry.
My original papers on this in Nature (1962) and with Michael Cross in the Journal of Physiology (1963) have been cited many thousands of times. The story of what inspired me is most accessibly and briefly recounted in one of the Journal of Physiology’s Classical Perspective articles entitled ‘Light on Platelets’ (J.Physiol., vol. 568, pp713-714, 2005).